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Article pubs.acs.org/IC Cite This: Inorg. Chem. 2017, 56, 12809-12820 Synthesis, Structure, and Luminescence of Copper(I) Halide Complexes of Chiral Bis(phosphines) Sarah K. Gibbons,† Russell P. Hughes,† David S. Glueck,*,† A. Timothy Royappa,‡ Arnold L. Rheingold,‡ Robert B. Arthur,§ Aaron D. Nicholas,§ and Howard H. Patterson§ † 6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States Department of Chemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States § Department of Chemistry, University of Maine, Orono, Maine 04469, United States Downloaded via TEXAS WOMAN'S UNIV on December 9, 2018 at 04:16:49 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. ‡ S Supporting Information * ABSTRACT: For investigation of structure−property relationships in copper phosphine halide complexes, treatment of copper(I) halides with chiral bis(phosphines) gave dinuclear [Cu((R,R)-i-Pr-DuPhos)(μ-X)]2 [X = I (1), Br (2), Cl (3)], [Cu(μ-((R,R)-Me-FerroLANE)(μ-I)]2 (5), and [Cu((S,S)-Et-FerroTANE)(I)]2 (6), pentanuclear cluster Cu5I5((S,S)-EtFerroTANE)3 (7), and the monomeric Josiphos complexes Cu((R,S)CyPF-t-Bu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9); 1−3, 5, and 7−9 were structurally characterized by X-ray crystallography. Treatment of iodide 1 with AgF gave [Cu((R,R)-i-Pr-DuPhos)(μ-F)]2 (4). DuPhos complexes 1− 4 emitted yellow-green light upon UV irradiation at room temperature in the solid state. This process was studied by low-temperature emission spectroscopy and density functional theory (DFT) calculations, which assigned the luminescence to (M + X)LCT (Cu2X2 to DuPhos aryl) excited states. Including Grimme’s dispersion corrections in the DFT calculations (B3LYP-D3) gave significantly shorter Cu−Cu distances than those obtained using B3LYP, with the nondispersion-corrected calculations better matching the crystallographic data; other intramolecular metrics are better reproduced using B3LYP-D3. A discussion of the factors leading to this unusual observation is presented. ■ INTRODUCTION Copper(I) phosphine halide complexes are common precursors in catalysis,1 and their luminescent properties have often been investigated.2 For both applications, varying the phosphine enables rational control of the structure and properties of the copper complex. For example, the structure of [Cu(diphos)(X)]n (X = halide) depends on the chelating bis(phosphine) diphos (Chart 1). Three-coordinate monomers A are known for bulky chelates, such as Cu(dapBz)(I),3 or for ligands with large bite angles, as in Cu(Josiphos)(Br) (R = Cy, R′ = Ph; Chart 1).4 Fourcoordinate dimers B, with approximately tetrahedral copper, chelating bis(phosphines), and bridging halides, are the most common, with ligands such as dppf,5 dppBz,6 Binap,7 and dppp.8 Finally, four-coordinate dimers C, with both halides and bis(phosphines) bridging, are often observed with flexible ligands having larger bite angles, as in [Cu(μ-diop)(μ-X)]2 (X = Cl, I)9 or CuI complexes of dppb and dppPent.10 The free energies of the isomers A−C are often similar (Chart 1), so mixtures of isomers and interconversion between them can be observed. For example, both monomeric and dimeric [Cu(Josiphos)(Br)]n could be isolated in pure form; they underwent solvent-dependent interconversion.4 Similarly, both structures B and C were observed in the same crystal for © 2017 American Chemical Society Chart 1. Structures of [Cu(diphos)(X)]n Complexes [Cu(Ph-BPE)(Cl)]2.11 Small changes may determine the observed structure; replacing PPh2 groups in dppBz with P(oTol)2 donors resulted in a change from dimer B to monomer A,3,6 while extending the linker between PPh2 donors by one Received: June 19, 2017 Published: October 24, 2017 12809 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Scheme 1. Synthesis of Complexes 1−9 Figure 1. ORTEP diagrams of 1·Et2O (left), 2·THF (middle), and 3·THF (right). The solvent molecules are not shown. CH2 group (dppp → dppb) switched diphos from a chelate in B to a bridging ligand in C.8,10 Luminescent properties have been reported for complexes of all three structure types, including Cu(dapBz)(I) (A),3 [Cu(Binap)(I)]2 (B),12 and [Cu(μ-diop)(μ-Cl)]2 (C).9b Changing the halide and/or the bis(phosphine) caused changes of the emission color and quantum yield; the resulting structure−property relationships are potentially valuable in the design and synthesis of new emitters with tailored photophysical properties.2 With this background, we report here the synthesis, structure, and luminescent properties of new copper halide complexes with the chiral bis(phospholanes) i-Pr-DuPhos and MeFerroLANE,13 the analogous chiral bis(phosphetane) EtFerroTANE,14 and the P(t-Bu)2-substituted Josiphos ligands CyPF-t-Bu and PPF-t-Bu (Scheme 1).15 In earlier work, Cu(iPr-DuPhos) complexes were formed in situ and used as precursors in asymmetric catalysis, but these starting materials were not isolated and their structures were not determined.16 In contrast, the ferrocene-based Me-FerroLANE, Et-FerroTANE, and t-Bu-Josiphos derivatives, with larger bite angles, have not yet been used in the preparation of copper complexes or in copper-catalyzed reactions. Besides providing structural in- formation for catalysis, we hoped to investigate structure− property relationships in luminescence by comparing the phospholane/phosphetane/dialkylphosphino donors to the more commonly used PAr2 groups shown in Chart 1. ■ RESULTS AND DISCUSSION Synthesis and Structure of Cu(diphos*) Halide Complexes. Treatment of copper halides with (R,R)-i-PrDuPhos gave the dimers [Cu((R,R)-i-Pr-DuPhos)(X)]2 [X = I (1), Br (2), Cl (3)] as light-yellow solids (Scheme 1). The analogous fluoride 417 was prepared from iodide 1 and AgF.18 Similar reactions of CuI with (R,R)-Me-FerroLANE and (S,S)Et-FerroTANE yielded orange [Cu((R,R)-Me-FerroLANE)(I)]2 (5) and [Cu((S,S)-Et-FerroTANE)(I)]2 (6), respectively. The cluster Cu5I5((S,S)-Et-FerroTANE)3 (7), which was originally observed as a byproduct in the synthesis of 6, was prepared rationally using a 5:3 ratio of CuI and the ligand. Finally, CuI and t-Bu-Josiphos ligands gave Cu((R,S)-CyPF-tBu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9) as red-orange crystals. With Me-FerroLANE and Et-FerroTANE, these syntheses also gave small amounts of phosphine oxides, presumably via oxidation by copper(II) impurities in CuI; similar observations 12810 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry were made with Me-DuPhos earlier.19 Using commercially available higher-purity CuI avoided this problem for the MeFerroLANE complex 5, but we were not able to obtain pure bulk samples of Et-FerroTANE complexes 6 and 7 (see the Experimental Section for details). Complexes 1−9 were characterized spectroscopically (see below), by elemental analyses, and, for 1−3, 5 and 7−9, by Xray crystallography (Figures 1−4, Table 1, and the Supporting Information, SI). as were the P−Cu−P bite angles, but the DuPhos complexes featured larger X−Cu−X and Cu−X−Cu angles, associated with longer Cu−Cu distances. As in 1−3, the structures of 5 and 7 also contained distorted tetrahedral copper, supported by bridging bis(phosphines). In 5, the large P−Cu−P angle of 123.78(4)° was accompanied by a diamond-shaped Cu2I2 core including acute Cu−I−Cu angles (63.5°) and a Cu−Cu distance of 2.8694(9) Å. Similar bridging coordination in copper complexes is known for dppf20 and its P(t-Bu)2 analogue dtbpf21 but was not previously reported with any metal for Me-FerroLANE. The structure of cluster 7 featured both a chelate Et-FerroTANE [bite angle = 112.5(3)°] and two bis(phosphetanes) bridging two coppers, with an unusual Cu5I5 core (Figure 3).22 As with Me-FerroLANE in 5, bridging coordination of Et-FerroTANE had not been observed earlier. For the three different types of bridging iodides in 7, slightly longer Cu−I bonds were generally observed with larger iodide coordination numbers [for μ4-I3, Cu2−I = 2.769(2) Å and Cu3−I = 2.740 Å; for μ3-I2, Cu1−I = 2.675(2) Å, Cu2−I = 2.680(3) Å, and Cu3−I = 2.650(2) Å; for μ2-I1, Cu2−I = 2.660(3) Å and Cu3−I = 2.669(2) Å]. As described in the Introduction, Cu(Josiphos)(Br) complexes with PPh2 and PCy2 donors formed three-coordinate monomers or four-coordinate, bromide-bridged dimers.4 As expected, increasing the size of the phosphine [P(t-Bu)2] and the halide (iodide) yielded monomeric crystals of 8 and 9. Their structures (Figure 4) were similar to those of a related monomeric bromide complex, with distorted trigonal-planar coordination and Josiphos bite angles of 106.21(3)° and 103.62(7)°. As seen in Table 2, changing the phosphine substituents (t-Bu/Cy/Ph) and halide (I/Br) had only small effects on the structures. Copper complexes 1−9 are the first examples with these ligands. For future applications, it would be useful to determine their coordination modes spectroscopically, without recourse to X-ray crystallography. Therefore, we investigated their 31P{1H} NMR spectra, which all featured broad signals typical of copper phosphine complexes.23 Binding i-Pr-DuPhos to the copper halides resulted in 31P NMR coordination chemical shifts from δ −11.2 (free ligand)24 to −2.8 (F), −7.1 (Cl), −5.6 (Br), or −3.6 (I; all data in CDCl3). Shifts similar in magnitude were observed for the CuX complexes of the related o-phenylenelinked bis(phosphine) dppBz in 10−12, from δ −13.0 (ligand)25 to −17.2 (Cl), −19.0 (Br), and −22.1 (I).6 Similarly, the Me-FerroLANE 31P NMR chemical shift moved from δ −1.1 (ligand) to 3.5 (CDCl3) or −8.9 (C6D6) upon formation of 5. This surprisingly large, reversible, solvent-dependent chemical shift difference might arise from a structural change, for example, isomerization between bridging and chelate bis(phosphines), but we have no direct evidence for this possibility. The Et-FerroTANE 31P NMR signal26 moved from δ 13.1 to two broad signals at δ 2.9 and −0.5 (CD2Cl2) in 7, which, on the basis of their relative intensity, were assigned to chelating and bridging Et-FerroTANE, respectively. This assignment is consistent with the 31P NMR shift of [Cu(EtFerroTANE)(I)]2 (6; δ 4.7 in CD2Cl2), which likely contains a bridging bis(phosphine), as in 5. For chelating t-Bu-Josiphos ligands, large P(t-Bu)2 and small PCy2 or PPh2 coordination chemical shifts were observed, from δ 46.6 and −15.4 to δ 26.5 and −14.7 for CyPF-t-Bu in 8 and from δ 45.9 and −26.1 to δ 32.1 and −22.3 for PPF-t-Bu in 9.27 This chelation led to large increases in JPP from 16 to 154 Hz and from 50 to 160 Hz for 8 and 9, respectively. Figure 2. ORTEP diagram of 5. Figure 3. ORTEP diagram of 7, showing μ4-I3, μ3-I2, and μ2-I1, as well as chelating Et-FerroTANE (P1) and bridging Et-FerroTANE (P2/ P3). The isomorphous structures of complexes 1−3 contained the extensively investigated Cu2(μ-X)2 core,2 which here was puckered in a “butterfly” geometry with distorted tetrahedral coordination at copper. Unfortunately, we were not able to grow suitable crystals of the fluoride complex 4 for comparison, but its structure and those of 1−3 were investigated computationally (see below). Table 1 summarizes the X-ray crystallographic structural data for 1−3 in comparison to those for the dppBz analogues 10−12, which contain the same ophenylene linker but PPh2 donors in place of the phospholanyl groups.6 The Cu−X and Cu−P bond lengths were very similar, 12811 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Figure 4. ORTEP diagrams of 8 (left) and 9·CH2Cl2 (right) with the solvent molecules omitted. Table 1. Average Values of Selected Bond Lengths (Å) and Angles (deg) in [Cu(i-Pr-DuPhos)(X)]2 Dimers 1−3 and the dppBz Analogues 10−126 no. X Cu−X Cu−P P−Cu−P P−Cu−X X−Cu−X Cu−X−Cu Cu···Cu CuX2/Cu′X2 dihedral angle 1 2 3 I Br Cl 2.6423(9) 2.4895(7) 2.3649(14) 2.255(2) 2.2536(12) 2.2500(14) 91.77(7) 91.51(4) 91.55(5) 116.32(6) 118.08(6) 118.08(6) 101.45(3) 95.40(5) 95.40(5) 76.28(3) 82.09(5) 82.09(5) 3.264 3.208 3.106 154.61 154.50 154.65 10 11 12 I Br Cl 2.635(9) 2.478(7) 2.359(1) 2.281(2) 2.259(1) 2.254(2) 87.5(6) 89.2(4) 89.0(5) 114.24(6) 114.66(4) 116.38(6) 109.3(3) 107.6(2) 102.3(4) 66.7(2) 69.8(2) 74.8(4) 2.898 2.837 2.866 143.7 124.5 150.9 Table 2. Selected Bond Lengths (Å) and Angles (deg) in Cu(t-Bu-Josiphos)(I) Complexes 8 and 9 and the Analogous Bromide Complex Cu(PPF-t-Bu)(Br) Josiphos/X CyPF-t-Bu/ I (8) PPF-t-Bu/I (9· CH2Cl2) rac-PPFCy/Bra enant-PPFCy/Bra R/R′ Cu−X Cu−P1 Cu−P2 X−Cu−P1 X−Cu−P2 P1−Cu−P2 ref t-Bu/Cy 2.5187(4) 2.2437(8) 2.2562(8) 123.34(2) 130.41(2) 106.21(3) this work t-Bu/Ph 2.4970(9) 2.232(2) 2.2563(19) 126.16(6) 130.19(6) 103.62(7) this work Cy/Ph 2.3130(3) 2.2395(6) 2.2429(5) 130.20(2) 125.88(2) 102.51(2) 4b Cy/Ph 2.3232(5) 2.2659(7) 2.2626(8) 130.86(2) 126.69(2) 101.97(3) 4b Figure 5. UV−vis spectra of 1−4 in CH2Cl2 (10−4 M). 6). Emission also occurred in poly(methyl methacrylate) (PMMA) films formed by spin-coating of CH2Cl2 solutions (see the SI).29 In contrast, no emission was observed in ferrocene-based 5−9. a The structure of the bromide complex in ref 4b was determined separately with racemic and enantiomerically pure Josiphos ligands. All complexes in this work were prepared with enantiomerically pure ligands. Photophysical Properties of Complexes 1−4. As shown in Figure 5, varying the halide in DuPhos complexes 1−4 had little effect on their UV−vis spectra in CH2Cl2.28 For 1−3, the intense peaks around 360 nm had extinction coefficients of ∼104 M−1, consistent with their assignment, as in similar complexes, to (M + X)LCT charge-transfer processes.6 Solid samples of the DuPhos complexes 1−4 emitted yellowgreen light upon UV irradiation at room temperature (Figure Figure 6. Samples of 1−4 at room temperature under ambient light (above) and upon UV irradiation (below). 12812 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry The luminescence of 1−4 was further probed by lowtemperature spectroscopy (Figure 7 and Table 3). The Table 4. Comparison of the Gas-Phase Cu−Cu Distances and CuCl2Cu Bridge Fold Angles (Dihedral Angles between the CuCl2 Planes) As Calculated by DFT (B3LYP-D3 and B3LYP) and Determined Crystallographically in the Solid State Cu−Cu distance (Å) I (1) Br (2) Cl (3) F (4) CuCl2Cu fold angle (deg) B3LYP-D3 B3LYP X-ray B3LYP-D3 B3LYP X-ray 3.061 2.862 2.861 2.610 3.426 3.254 3.180 2.909 3.264 3.208 3.106 143.2 145.4 146.9 146.2 157.6 164.4 162.4 168.9 154.6 154.5 154.7 Figure 7. Luminescence spectra of 1−4 at 77 K. All emission spectra were obtained using 400 nm as the excitation wavelength. All excitation spectra were obtained using the emission peak maximum. Table 3. Photophysical Data for 1−4 (Solid State, 77 K) compound (X) 1 2 3 4 (I) (Br) (Cl) (F) λex (nm)a λem (nm) apparent Stokes shift (cm−1)b quantum yield (298 K) 397 372 374 384 532 549 542 539 6390 8670 8290 7490 0.039(3) 0.017(2) <0.01 <0.01 Figure 8. DFT-calculated gas-phase structures for 3 using the B3LYPD3 (blue) and B3LYP (bronze) functionals, looking down the Cl−Cl vector. λmax from the excitation spectrum. Energy difference between the absorption and emission peaks, which may not involve the same excited state. a b between each Cl−Cu−Cl plane is significantly larger and the Cu−Cu distance significantly longer than when dispersion corrections are included; analogous trends were observed for the iodide, bromide, and fluoride analogues, although no crystallographic data are available for the fluoride. Thus, the dispersion-corrected functional underestimates the fold angle in the bridge, with a resultant large decrease in the Cu−Cu distance. We suggest that, in the gas-phase calculation, in which no intermolecular interactions are included, many small intramolecular dispersion attractions between the ligand C−H bonds are sufficient to cause additional folding in the bridge and reduction in the Cu−Cu distance, as shown in Figure 8, while in the solid state, these intramolecular interactions are counterbalanced by intermolecular interactions to give a more planar bridge and a longer Cu−Cu distance. This illustrates that care must be used when validating the quality of gas-phase DFT results by their agreement, or lack thereof, with crystallographic data. We will have more to say about the solution structure later. As shown in Figure 9 for the chloro complex 3, the computed highest occupied molecular orbitals (HOMOs) in the halide series involve the interactions of Cu 3d, halide p, and out-of-phase P lone-pair combinations, and the lowest unoccupied molecular orbital (LUMO) is an entirely ligandbased π* molecular orbital within the i-Pr-DuPhos o-phenylene group. Time-dependent DFT (TD-DFT) methods were used to compute the UV−vis spectra of 1−4.29 There is reasonable agreement between the computed gas-phase spectra (Figure 10) and the experimental ones in CH2Cl2 solution. In excitation profiles in the solid state at 77 K, with λmax ranging from 372 to 397 nm, were similar to the room temperature UV−vis spectra in CH2Cl2 solution, except for the low-energy absorption observed in solution for the fluoride 4.28 Quantum yields measured for solid samples at room temperature in air are included in Table 3. Consistent with qualitative observations, the iodide complex 1 had the brightest emission under these conditions. Electronic Structure of Complexes 1−4: Computational Studies. To investigate the photophysical properties of DuPhos complexes 1−4, we calculated the structures of their ground and excited states using density functional theory (DFT) methods (see the Experimental Section and SI for details). For the ground states, the computed (gas-phase) structures were in reasonable agreement with those observed by X-ray crystallography in the solid state. The calculations slightly overestimated the Cu−X and Cu−P bond lengths, with the best agreement for functionals including a dispersion correction.30 However, structures optimized with the B3LYP-D3 functional, which includes dispersion corrections, showed significantly larger deviations from the crystallographic metrics within the Cu2X2 core, especially in the Cu···Cu distances; these core metrics were better reproduced by B3LYP calculations without dispersion (Table 4). This is an unusual deviation from current thinking, in which inclusion of dispersion is usually strongly advocated.30 A superimposition of structures of the chloride dimer 3 determined using both functionals is shown in Figure 8. As shown in Table 4, without dispersion corrections, the fold angle 12813 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Figure 9. Calculated (B3LYP-D3) HOMO (left) and LUMO (right) for 3. consistent with weaker bonding in both the Cu2X2 core and the DuPhos arene ring. The superimposition also illustrates the significant twisting of the DuPhos ligand containing the long C−C bond relative to the ground state. Calculations without dispersion gave similar results but with less folded Cu2X2 cores, as was also observed for the ground states. Structure−Property Relationships in the Photophysical Properties of 1−4. As in structurally similar copper(I) phosphine halide complexes, we propose that excitation from a Cu2X2-based HOMO to a π*-acceptor phosphine LUMO (DuPhos o-phenylene group)6 in 1−4 leads to (M + X)LCT excited states, for which the structures of the lowest-energy singlet states were optimized. By analogy to previous work,6 we assume that the emissive excited states have (M + X)LCT character, but cannot tell if they are singlets or triplets. In related complexes, (M + X)LCT emission energy can often be tuned by changing the halide and/or phosphine to control the energy of the HOMO and/or LUMO.31 Table 5 compares low-temperature emission spectral data for 1−3 and analogous complexes, which all also contain P-aryl acceptor groups. Because related fluoride complexes are rare, data for 4 are not included. In some cases (numbers 2−4), emission wavelengths showed a smooth dependence on the halide, in the order Cl > Br > I. This behavior has been rationalized on the basis of the relative ligand-field strengths (Cl > Br > I), which make the Cu2X2 HOMO highest in energy for X = Cl, leading to reduced emission energy and higher wavelength.6,32,33 However, in some closely related structures, the halide had little effect (entries 5 and 6).34,35 Our data for 1−3, likewise, did not show a smooth trend (number 1; note that the emission maximum for fluoride 4 was at 539 nm). It has been proposed that such behavior reflects an important contribution from the phosphine donor orbitals to the HOMO.2a A more direct test of the effects of switching from the PPh2 donor to the phospholane group comes from comparing data for 1−3 with the dppBz analogues 10−12 (Table 5, entries 1 and 2). The ligand field of the alkylphosphine donor phospholane should be greater than that of the arylphosphine PPh2 group.36 This should increase the HOMO energy, reducing the emission energy and increasing the wavelength, as described above for the halides. This argument is consistent with the literature emission data for the phosphinopyridine Figure 10. Computed (B3LYP) UV−vis spectra of 1−4. particular, the calculations reproduced the similarity of the spectra and their lack of dependence on the halide. Notably, the analogous spectral calculations on the more folded B3LYP-D3 structures gave poorer agreement with experiment (see the SI), suggesting that the solution structures of these dimers may be more similar to the less folded solid-state ones, in which intramolecular dispersive forces are less controlling of the structure. Optimization of the first singlet excited state was also carried out for each compound using TD-DFT methods. An overlay of the computed structures of the ground and first excited states for chloride complex 3 (Figure 11) is consistent with the expected results of a HOMO−LUMO transition and an (M + X)LCT emissive excited state. In particular, the excited state included longer Cu−X and Cu···Cu distances, with a significantly longer C−C bond in one DuPhos aryl group, Figure 11. Overlay of the computed (B3LYP-D3) ground-state (red) and excited-state (blue) structures for 3. 12814 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry The synthesis and structural characterization of i-Pr-DuPhos complexes 1−3 established the expected chelation, which is consistent with previous hypotheses on the mechanisms of Cu(i-Pr-DuPhos)-catalyzed reactions.16 The larger bite angles of the ferrocene-linked bis(phospholane) Me-FerroLANE and bis(phosphetane) Et-FerroTANE resulted in different structures, with chelating and/or bridging coordination in 5 and 7. The combination of large bite angles, bulky phosphine substituents, and iodide ligands led to monomeric t-BuJosiphos complexes 8 and 9, as expected in comparison to related complexes.4 Related structure−property relationships were observed in the photophysical properties of emissive complexes 1−4, which contain the better donor phospholanes in comparison to analogues with the more commonly used diarylphosphino groups. As shown by the comparison in Table 5, however, varying the halide in the dimers [Cu(diphos)(X)]2 may result either in smooth trends in the emission energy or in discontinuities, as in our data for 1−4; further structure− property studies, including additional study of rare fluoride complexes, may enable better control of these parameters. We also observed that a better match of the Cu2X2 core crystal structure and the solution UV−vis spectra to computed results was obtained in DFT calculations when dispersion was not included, which may be more general in such conformationally flexible systems. Table 5. Emission Spectroscopic Data (nm) for 1−3 and Related [Cu(diphos)(X)]2 Complexesa ■ a Data from solid-state emission spectra at 77 K, except for entry 6 (room temperature in CH2Cl2 solution). EXPERIMENTAL SECTION General Experimental Details. Unless otherwise noted, all reactions and manipulations were performed in dry glassware under a nitrogen atmosphere at ambient temperature in a glovebox or using standard Schlenk techniques. Pentane, CH2Cl2, ether, tetrahydrofuran (THF), and toluene were dried over alumina columns similar to those described by Grubbs et al.38 NMR spectra were recorded with 500 or 600 MHz Bruker spectrometers. 1H or 13C NMR chemical shifts are reported versus Me4Si and were determined by reference to the residual 1H or 13C solvent peaks. 31P NMR chemical shifts are reported versus H3PO4 (85%) used as an external reference. Coupling constants are reported in hertz, as absolute values. Unless indicated, peaks in the NMR spectra are singlets. Quantitative Technologies Inc./Intertek Pharmaceutical Services (Whitehouse, NJ) or Atlantic Microlab (Norcross, GA) provided elemental analyses. Mass spectrometry was performed at the University of Illinois. Reagents were from commercial suppliers. [Cu((R,R)-i-Pr-DuPhos)(I)]2 (1). To a slurry of copper(I) iodide (44 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-i-PrDuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting yellow solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of pale-yellow powder and yellow crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A pale-yellow crystalline solid formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.140 g, 99%). The solid was washed with pentane to remove a small amount of free i-Pr-DuPhos. A sample recrystallized from CH2Cl2 contained 0.75 equiv of that solvent, according to 1H NMR integration and elemental analysis. Anal. Calcd for C52H88Cu2I2P4·0.75CH2Cl2: C, 49.43; H, 7.04. Found: C, 49.74; H, 7.08. HRMS. Calcd for C52H88Cu2I2P4: m/z 1216.2518. Found: m/z 1216.2498. 31P{1H} NMR (CDCl3, 25 °C): δ −3.6. 1H NMR (CDCl3, 25 °C): δ 7.70−7.69 (m, 4H, Ar), 7.47−7.46 (m, 4H, Ar), 2.53−2.50 (br m, 4H, CH), 2.31−2.23 (br m, 8H, CH2), 2.20− 2.15 (br m, 4H, CH), 2.09−2.06 (br m, 4H, CH), 1.79−1.74 (overlapping m, 4H, CH2), 1.71−1.64 (br m, 4H, CH2), 1.26−1.22 (br m, 4H, CH), 1.11 (d, J = 7, 12H, i-Pr Me), 0.94 (d, J = 7, 12H, i-Pr Me), 0.75 (d, J = 7, 12H, i-Pr Me), 0.68 (d, J = 7, 12H, i-Pr Me). 13 C{1H} NMR (CDCl3, 25 °C): δ 143.6 (t, J = 21, quat Ar), 134.7 (t, J complexes in Chart 2 containing PPh2 and phospholane donors, a rare example of this comparison,37 and it also works Chart 2. Emission Wavelength Data (Solid State, Room Temperature) for Phosphinopyridine CuI Complexes Containing Diphenylphosphino or Phospholane Donors in rationalizing the increased emission wavelength for 1 and 2 in comparison to their dppBz analogues 10 and 11. The similar emission wavelengths for 3 and 12 may reflect overlaid halide effects. ■ CONCLUSIONS Structure−Property Relationships. As described in the Introduction (Chart 1), changing the bis(phosphine) controls the structure and properties of [Cu(diphos)(X)]n complexes, and we have observed similar relationships here with several chiral bis(phosphines) new to copper coordination chemistry. 12815 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry NMR (CDCl3, 25 °C): δ −2.8. 31P{1H} NMR (THF-d8, 25 °C): δ −6.2. 19F NMR (THF-d8, 25 °C): δ −140.3. 1H NMR (THF-d8, 25 °C): δ 7.82−7.80 (m, 4H, Ar), 7.48−7.46 (m, 4H, Ar), 2.62−2.56 (br m, 4H, CH), 2.32−2.19 (br m, 16H, overlapping CH2 and CH), 1.84 (apparent dq, J = 6, 4H, CH2), 1.79−1.70 (br m, 4H, CH2), 1.42 (very br, 4H, CH), 1.16 (d, J = 7, 12H, i-Pr Me), 0.96 (d, J = 8, 12H, i-Pr Me), 0.72 (d, J = 7, 12H, i-Pr Me), 0.68 (d, J = 6, 12H, i-Pr Me). 13 C{1H} NMR (THF-d8, 25 °C): δ 144.8 (t, J = 21, quat Ar), 135.4 (t, J = 3, CH), 130.1 (CH), 52.8 (t, J = 8, CH), 51.4 (t, J = 8, CH), 32.6 (CH2), 31.3 (t, J = 9, CH), 29.4 (CH), 29.1 (CH2), 25.0, (br, i-Pr Me), 24.2 (br, i-Pr Me), 21.1 (i-Pr Me), 20.9 (br, i-Pr Me). [Cu((R,R)-Me-FerroLANE)(I)]2 (5). Treatment of CuI with MeFerroLANE gave 5; the formation of impurities in this reaction depended on the solvent and the source/purity of copper iodide, as summarized below. To a slurry of CuI (Strem, 98%; 22 mg, 0.12 mmol) in 2 mL of THF was added a solution of (R,R)-Me-FerroLANE (37.5 mg, 0.12 mmol) in 2 mL of THF, and the resulting dark-orange solution was stirred for 20 min. The solution was concentrated under vacuum to give an orange solid. The solid was redissolved in THF; slow evaporation gave a mixture of orange crystals and amorphous material (0.058 g, 86%), which contained an unidentified impurity (31P{1H} NMR: δ 62.9). In a similar experiment, the orange solid was washed with ether and pentane; X-ray-quality crystals were obtained from the pale-orange pentane solution. No impurities were formed in a similar preparation in toluene, which gave orange crystals after recrystallization from toluene/pentane at −20 °C. Similarly, no impurities were observed with higher-purity CuI in THF. To a slurry of “Puratronic” CuI (Alfa Aesar, 99.999%; 22 mg, 0.12 mmol) in 1 mL of THF was added a solution of (R,R)-Me-FerroLANE (47.5 mg, 0.12 mmol) in 2 mL of THF. The resulting bright-orange solution was stirred for 20 min and then filtered through Celite. Concentration under vacuum gave an analytically pure orange powder (53 mg, 42% yield). Anal. Calcd for C44H64Cu2I2P4Fe2: C, 43.70; H, 5.33. Found: C, 43.51; H, 5.24. HRMS. Calcd for C44H64Cu2IP4Fe2 [(M − I)+]: m/z 1081.0294. Found: m/z 1081.0278. Because the 31P NMR spectra were solvent-dependent, we report NMR data in different solvents. 31 1 P{ H} NMR (CDCl3, 25 °C): δ 3.5. 31P{1H} NMR (C6D6, 25 °C): δ −8.9. 1H NMR (CDCl3, 25 °C): δ 4.55 (4H, Cp CH), 4.34 (overlapping, 8H, Cp CH), 4.20 (4H, Cp CH), 2.75−2.72 (br m, 4H, CH), 2.43−2.41 (br m, 4H, CH), 2.27−2.23 (br m, 4H, CH2), 2.02− 1.98 (br m, 4H, CH2), 1.62 (apparent q, J = 10, 12H, Me), 1.51−1.45 (br m, 4H, CH2), 1.34−1.30 (br m, 4H, CH2), 0.90 (apparent q, J = 7, Me). 1H NMR (C6D6, 25 °C): δ 4.66 (4H, Cp CH), 4.17 (4H, Cp CH), 3.97 (4H, Cp CH), 3.87 (4H, Cp CH), 2.83 (4H, CH), 2.51− 2.49 (br m, 4H, CH), 2.03 (4H, CH2), 1.93 (4H, CH2), 1.89 (apparent q, J = 8, 12H, Me), 1.51 (4H, CH2), 1.25−1.21 (br m, 4H, CH2), 1.19 (apparent q, J = 6, 12H, Me). All of the signals were broad. 13 C{1H} NMR (CDCl3, 25 °C): δ 76.4 (t, J = 12, Cp CH), 73.6 (br t, quat Cp), 73.3 (Cp CH), 71.1 (Cp CH), 70.5 (Cp CH), 36.0 (CH2), 35.6 (CH2), 34.9 (t, J = 9, CH), 34.0 (t, J = 9, CH), 20.9 (t, J = 9, Me), 14.9 (Me). 13C{1H} NMR (C6D6, 25 °C): δ 77.2 (t, J = 10, Cp CH), 75.4 (br t, quat C), 72.8 (Cp CH), 70.7 (Cp CH), 69.7 (Cp CH), 36.2 (CH2), 36.0 (t, J = 8, CH), 35.3 (CH2), 35.0 (t, J = 8, CH), 21.3 (t, J = 7, Me), 16.3 (Me). Cu2I2((S,S)-Et-FerroTANE)2 (6). As with the Me-FerroLANE analogue 5, impurities were formed in the reaction of Et-FerroTANE and CuI. Varying the solvent (THF or toluene) and/or the CuI purity (98% to 99.9999%) did not avoid this problem, and adding copper wire, to reduce putative copper(II) impurities,39 was also unsuccessful, so we were not able to get pure bulk samples of 6. In a typical synthesis, to a slurry of CuI (Strem, 98%; 44 mg, 0.23 mmol) in 2 mL of THF was added a solution of (S,S)-Et-FerroTANE (102 mg, 0.23 mmol) in 1 mL of THF. The resulting orange solution was stirred for 20 min and then concentrated under vacuum to give an orange solid (134 mg, 92%). 31P NMR spectra of the bulk solid (CD2Cl2) showed an impurity signal at 64.3 ppm (7%), which was present in all noncrystalline material. The 31P NMR spectrum of a portion of the original reaction mixture (THF) showed peaks due to the impurity (δ 61.2), plus additional signals at δ 56.7 (trace), 12.2 (Et-FerroTANE), = 2, CH), 129.8 (CH), 52.4 (t, J = 9, CH), 51.3 (t, J = 9, CH), 32.8 (CH2), 30.7 (t, J = 8, CH), 28.7 (CH), 28.3 (CH2), 24.9 (t, J = 3, i-Pr Me), 23.8 (t, J = 5, i-Pr Me), 21.5 (t, J = 3, i-Pr Me), 20.3 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(Br)]2 (2). To a slurry of copper(I) bromide (33 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-iPr-DuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting yellow solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of yellow powder and yellow crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A yellow crystalline solid was formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.126 g, 97%). X-ray crystallography showed that the crystals were 2·THF. Anal. Calcd for C52H88Cu2Br2P4: C, 55.56; H, 7.89. Found: C, 55.56; H, 8.05. HRMS. Calcd for C52H88Cu2Br2P4: m/z 1120.2795. Found: m/z 1120.2767. 31P{1H} NMR (CDCl3, 25 °C): δ −5.6. 1H NMR (CDCl3, 25 °C): δ 7.69 (br m, 4H, Ar), 7.46 (br m, 4H, Ar), 2.51 (br m, 4H, CH), 2.25 (br m, 8H, CH2), 2.13 (br m, 4H, CH), 2.03−2.02 (br m, 4H, CH), 1.79−1.74 (br m, 4H, CH2), 1.70−1.63 (br m, 4H, CH2), 1.2 (overlapping br m, 4H, CH), 1.1 (d, J = 7, 12H, i-Pr Me), 0.95 (d, J = 7, 12H, i-Pr Me), 0.77 (d, J = 6, 12H, i-Pr Me), 0.68 (d, J = 6, 12H, i-Pr Me). 13C{1H} NMR (CDCl3, 25 °C): δ 143.4 (t, J = 22, quat Ar), 134.6 (Ar), 129.7 (Ar), 52.4 (t, J = 9, CH), 51.5 (t, J = 8, CH), 33.0 (CH2), 30.8 (t, J = 9, CH), 28.7 (CH), 28.2 (CH2), 24.9 (br t, i-Pr Me), 23.7 (t, J = 5, i-Pr Me), 21.7 (br t, i-Pr Me), 19.7 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(Cl)]2 (3). To a slurry of copper(I) chloride (23 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-iPr-DuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting green solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of yellow-green powder and yellowgreen crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A yellow-green crystalline solid formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.107 g, 89%). The solid was washed with pentane to remove a small amount of free i-Pr-DuPhos. X-ray crystallography showed that the crystals were 3· THF. The cocrystallized solvent molecules in dimers 1−3 appeared to be lost easily, according to elemental analyses. For a sample that was recrystallized from THF/ether, the 1H NMR spectrum showed that it contained about 1.5 equiv of THF, which was apparently lost before analysis. Anal. Calcd for C52H88Cu2Cl2P4: C, 60.34; H, 8.57. Found: C, 59.91; H, 8.53. Another sample, recrystallized from CH2Cl2, analyzed for a monosolvate. Anal. Calcd for C52H88Cu2Cl2P4·CH2Cl2: C, 56.83; H, 8.10. Found: C, 56.52; H, 8.08. After this solid had been stored at room temperature for several days, its 1H NMR spectrum showed the presence of 0.6 equiv of CH2Cl2. HRMS. Calcd for C52H88Cu2Cl2P4: m/z 1032.3806. Found: m/z 1032.3789. 31P{1H} NMR (CDCl3, 25 °C): δ −7.1. 1H NMR (CDCl3, 25 °C): δ 7.72−7.69 (br m, 4H, Ar), 7.48−7.47 (br m, 4H, Ar), 2.55−2.50 (br m, 4H, CH), 2.29−2.23 (br m, 8H, CH2), 2.19−2.12 (br m, 4H, CH), 2.06−2.02 (br m, 4H, CH), 1.81−1.75 (apparent dq, 1JH−H = 13, 2JH−H = 13, 4H, CH2), 1.71−1.64 (apparent dq, 1JH−H = 12, 2JH−H = 12, 4H, CH2), 1.24−1.21 (br m, 4H, CH), 1.12 (d, J = 7, 12H, i-Pr Me), 0.97 (d, J = 7, 12H, i-Pr Me), 0.80 (d, J = 7, 12H, i-Pr Me), 0.71 (d, J = 7, 12H, i-Pr Me). 13C{1H} NMR (CDCl3, 25 °C): δ 143.4 (t, J = 22, quat Ar), 134.6 (Ar), 129.7 (Ar), 52.6 (t, J = 10, CH), 51.6 (t, J = 11, CH), 33.2 (CH2), 30.9 (t, J = 9, CH), 28.9 (CH), 28.3 (CH2), 25.0 (t, J = 3, i-Pr Me), 23.7 (t, J = 6, iPr Me), 21.8 (t, J = 7, i-Pr Me), 19.6 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(F)]2 (4). A solution of 1 (140 mg, 0.115 mmol) in 2 mL of THF was added to AgF (58 mg, 0.45 mmol, 2.0 equiv). The resulting slurry was protected from light and sonicated for 1.5 h in an ultrasonic cleaning bath, then filtered through Celite to remove precipitate formed during the reaction. The solvent was removed under vacuum to give a yellow-gold solid (74 mg, 64%). The parent ion was not observed in the mass spectrum, in which the main peak was a [Cu2(i-Pr-DuPhos)2] fragment. MS. Calcd for C52H88Cu2 [(MH − 2F)+]: m/z 963.4. Found: m/z 963.5. 31P{1H} 12816 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry 103%). Recrystallization from CH2Cl2/pentane at −20 °C gave orange crystals, which X-ray crystallography showed were 9·CH2Cl2. Elemental analysis showed that another batch of crystals contained 0.5 equiv of CH2Cl2. Anal. Calcd for C32H40CuFeIP2(CH2Cl2)0.5: C, 50.34; H, 5.33. Found: C, 50.42; H, 5.43. HRMS. Calcd for C32H40CuFeP2 [(M − I)+]: m/z 605.1251. Found: m/z 605.1258. 31P{1H} NMR (CH2Cl2, 25 °C): δ 32.1 (d, J = 160, P(t-Bu)2), −22.3 (d, J = 160, PPh2). 1H NMR (CDCl3, 25 °C): δ 8.07−8.04 (t, J = 8, 2H, Ar), 7.73 (t, J = 10, 2H, Ar), 7.49−7.46 (br m, 3H, Ar), 7.40−7.39 (br m, 3H, Ar), 4.58 (1H, Cp), 4.39 (1H, Cp), 4.08 (1H, Cp), 4.04 (5H, Cp), 3.47−3.46 (br m, 1H, CHMe), 1.99 (t, J = 7, 3H, CHMe), 1.37 (d, J = 13, 9H, tBu), 1.17 (d, J = 13, 9H, t-Bu). 13C{1H} NMR (CDCl3, 25 °C): δ 135.4 (d, J = 26, quat Ar), 134.4 (d, J = 15, Ar CH), 134.1 (d, J = 16, Ar CH), 133.2 (dd, J = 26, 9, quat Ar), 130.2 (Ar CH), 130.1 (Ar CH), 128.8 (d, J = 3, Ar CH), 128.7 (d, J = 2, Ar CH), 94.5 (dd, J = 20, 7, quat Cp), 75.9 (d, J = 24, quat Cp), 74.8 (d, J = 4, Cp CH), 71.0 (d, J = 8, Cp CH), 70.4 (Cp CH), 68.9 (d, J = 6, Cp CH), 37.2 (d, J = 4, CMe3), 35.3 (d, J = 5, CMe3), 33.0 (CHMe), 31.8 (d, J = 7, CMe3), 31.2 (d, J = 7, CMe3), 17.4 (d, J = 5, CHMe). UV−Vis Spectroscopy. UV−vis spectra were recorded on 10−4 M CH2Cl2 solutions of complexes 1−4 in a quartz cuvette at 298 K, using a Jasco V-630 spectrophotometer. Emission Spectroscopy. Luminescence spectra were collected for microcrystalline samples 1−4. Steady-state luminescence scans were run at 77 K. Liquid nitrogen was used as the coolant. Spectra were taken with a Quantamaster-1046 photoluminescence spectrophotometer from Photon Technology International. This spectrometer uses a 75 W xenon arc lamp combined with two excitation monochromators and one emission monochromator. A photomultiplier tube at 800 V was used as the emission detector. The solid samples were mounted on a copper plate using nonemitting copper-dust high-vacuum grease. All scans were run under vacuum using a Janis ST-100 optical cryostat. Solid-State Quantum-Yield Measurements. Solid-state spectra were collected for microcrystalline samples 1−4 in air at 298 K using a Horiba PTI QM-400 spectrometer equipped with an integrating sphere. The excitation wavelength for all samples was 400 nm. Luminescence of 1−3 in PMMA Thin Films. A 5% (w/w) solution of 1 (0.03 g) in 0.4 mL of CH2Cl2 was added to PMMA (0.03 g, atactic beads, average molecular weight = 350000; Polysciences), and the mixture was stirred overnight. A total of 400 μL of the paleyellow solution were pipetted onto a glass slide and spin-coated at 800 rpm for 30 s. The resulting thin film was luminescent under UV light (see the SI for photographs). The procedure was similar for the chloride and bromide analogues 2 and 3, which formed pale-green and yellow-green solutions, respectively. DFT Calculations. For comparison, DFT calculations were carried out at both the University of Maine and Dartmouth College, with different basis sets. At Maine, calculations were performed on complexes 1−3 with the Gaussian09 program hosted by the University of Maine Advanced Computing Group. All calculations were performed with the B3LYP exchange correlation and the LANL2DZ basis set throughout. Experimental XRD geometries of 1−3 were used as the initial input structures for ground-state optimization calculations. Optimized ground-state structures were used for vertical energy calculations using the TD-DFT method. Molecular orbitals were reproduced using Avogadro 1.1.1. At Dartmouth, calculations were carried out using the hybrid B3LYP functional (both with and without the zero-damping, twobody-only D3 correction of Grimme et al.; see the text)40 and the LACV3P** basis set, which uses Los Alamos core potentials for the Cu atom41 and the 6-311G** basis for all lighter atoms,42 as implemented in the Jaguar suite of programs.43 Computed groundstate structures were confirmed as energy minima by calculating the vibrational frequencies using second derivative analytical methods and confirming the absence of imaginary frequencies. Geometries of first singlet excited states were optimized using TD-DFT calculations, as implemented in the Jaguar program. UV−vis spectra were also calculated at the B3LYP ground-state geometries using TD-DFT, with unrestricted occupations and including 48 excited states. and 3.3 (6). Slow evaporation of this solution gave orange crystals, which X-ray crystallography showed were Cu5I5((S,S)-Et-FerroTANE)3 (7). HRMS. Calcd for C48H72Cu2IP4Fe2 [(M − I)+]: m/z 1137.0920. Found: m/z 1137.0925. 31P{1H} NMR (CD2Cl2, 25 °C): δ 4.7 (6), 12.1 (free Et-FerroTANE, 5%), and unidentified signals at δ 64.3 (7%), 59.2 (trace), and 45.4 (trace). 1H NMR (CD2Cl2, 25 °C): δ 4.53 (4H, Cp CH), 4.41 (8H, Cp CH), 4.36 (4H, Cp CH), 2.64 (4H, FerroTANE CH), 2.43−2.37 (br m, 12H, CH2 and FerroTANE CH), 2.27−2.24 (br m, 4H, CH2), 2.00−1.95 (br m, 4H, CH2), 1.38−1.37 (br m, 4H, CH2), 1.10 (t, J = 7, 12H, Me), 0.76 (t, J = 8, 12 H, Me). 13 C{1H} NMR (CD2Cl2, 25 °C): δ 77.1 (t, J = 11, Cp), 74.5−74.4 (br m, quat C), 73.7 (Cp), 71.6 (Cp), 70.5 (Cp), 35.4 (t, J = 15, FerroTANE CH), 35.1 (t, J = 14, FerroTANE CH), 34.4 (t, J = 5, CH2), 27.0 (t, J = 6, CH2), 25.2 (CH2), 14.0 (t, J = 6, Me), 12.3 (t, J = 4, Me). Cu5I5((S,S)-Et-FerroTANE)3 (7). To a slurry of CuI (Strem, 98%; 44 mg, 0.23 mmol, 5 equiv) in 2 mL of THF was added a solution of (S,S)-Et-FerroTANE (60 mg, 0.14 mmol, 3 equiv) in 1 mL of THF, and the resulting solution was stirred for 20 min. The resulting orange solution was concentrated under vacuum to yield a bright-orange solid (98 mg, 92%). 31P NMR spectra of the bulk solid showed an impurity at δ 64.6 (4.8%), which was present in all noncrystalline material. A portion of the solid was redissolved in THF; slow evaporation gave orange crystals of 7, identified by X-ray crystallography. As with 6, varying the CuI purity and the solvent (THF or toluene) did not prevent impurity formation, and we could not isolate pure bulk samples of 7. 31 1 P{ H} NMR (CDCl3, 25 °C): δ 1.8 to −1.1 (br m, FerroTANE). 31 1 P{ H} NMR (CD2Cl2, 25 °C): δ 2.9 (br, chelating FerroTANE), −0.5 (br, bridging FerroTANE). 1H NMR (CD2Cl2, 25 °C): δ 5.11− 5.03 (br m, 4H, Cp), 4.91−4.86 (br m, 4H, Cp), 4.64−4.52 (br m, 16 H, Cp), 2.78 (4H, FerroTANE CH), 2.48 (overlapping, 4H, FerroTANE CH), 2.41 (overlapping, 8H, CH2 and FerroTANE CH), 2.12−1.92 (br m, 8H, CH2), 1.93−1.92 (br m, 8H, CH2), 1.25− 1.22 (br m, 12H, CH2), 1.06−1.02 (br m, 18H, Me), 0.70−0.67 (t, J = 7, 18H, Me). 13C{1H} NMR (CD2Cl2, 25 °C): δ 78.6−78.2 (br m, Cp), 72.7−72.2 (br m, Cp), 71.7 (br, Cp), 35.8 (d, J = 32, FerroTANE CH), 34.9 (d, J = 13, FerroTANE CH), 30.1 (d, J = 12, FerroTANE CH), 27.1−27.0 (br m, CH2), 25.2−25.1 (br m, CH2), 22.5 (Me), 13.8 (br, Me), 13.6 (br, Me), 12.5 (Me), 12.4 (d, J = 6, Me). Cu((R,S)-CyPF-t-Bu)(I) (8). To “Puratronic” copper(I) iodide (Alfa Aesar, 99.999%, 22 mg, 0.12 mmol) was added a solution of (R,S)CyPF-t-Bu (67 mg, 0.12 mmol) in 2 mL of CH2Cl2. The resulting solution was stirred for 10 min and then concentrated under vacuum to give an orange solid, which contained residual solvent (105 mg, 117%). Recrystallization from CH2Cl2/pentane at −20 °C gave orange crystals, which X-ray crystallography showed were 8. Anal. Calcd for C32H52FeP2CuI: C, 51.59; H, 7.04. Found: C, 51.69; H, 7.01. HRMS. Calcd for C32H52FeP2CuI: m/z 744.1234. Found: m/ z 744.1235. 31P{1H} NMR (CH2Cl2, 25 °C): δ 26.5 (d, J = 154, P(tBu)2), −14.7 (d, J = 154, PCy2). 1H NMR (CDCl3, 25 °C): δ 4.50 (1H, Cp), 4.37 (2H, Cp), 4.20 (5H, Cp), 3.18 (br, 1H, CHMe), 2.19− 2.11 (m, 4H, Cy CH and CH2), 1.95 (t, J = 7, 3H, CHMe), 1.89−1.63 (m, 10H, Cy CH2), 1.45 (d, J = 13, 9H, t-Bu), 1.39−1.30 (m, 6H, Cy CH2), 1.23−1.15 (m, 2H, Cy CH2), 1.03 (d, J = 13, 9H, t-Bu). 13 C{1H} NMR (CDCl3, 25 °C): δ 94.7 (dd, J = 14, 6, quat Cp), 74.7 (d, J = 14, quat Cp), 73.7 (Cp CH), 70.2 (d, J = 7, Cp CH), 69.7 (Cp CH), 68.0 (d, J = 4, Cp CH), 38.5 (d, J = 14, Cy CH), 37.1 (d, J = 3, CMe3), 35.1 (d, J = 6, CMe3), 33.8−33.7 (dd, J = 14, 7, Cy CH), 33.3 (CHMe), 31.2 (CMe3), 31.1 (CMe3), 30.9 (d, J = 10, Cy CH2), 29.2 (d, J = 5, Cy CH2), 28.6 (d, J = 5, Cy CH2), 27.6 (2 Cy CH2), 27.5 (d, J = 14, Cy CH2), 27.2 (d, J = 12, Cy CH2), 27.0 (d, J = 12, Cy CH2), 26.8 (d, J = 9, Cy CH2), 26.0 (d, J = 12, Cy CH2), 17.5 (d, J = 4, CHMe). Cu((R,S)-PPF-t-Bu)(I) (9). To “Puratronic” copper(I) iodide (Alfa Aesar, 99.999%, 22 mg, 0.12 mmol) was added a solution of (R,S)PPF-t-Bu (65 mg, 0.12 mmol) in 2 mL of CH2Cl2. The resulting solution was stirred for 10 min and then concentrated under vacuum to give an orange solid, which contained residual solvent (101 mg, 12817 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry ■ light-emitting diodes that exhibit delayed fluorescence. Dalton Trans. 2015, 44, 8369−8378. (4) (a) Harutyunyan, S. R.; López, F.; Browne, W. R.; Correa, A.; Peña, D.; Badorrey, R.; Meetsma, A.; Minnaard, A. J.; Feringa, B. L. On the Mechanism of the Copper-Catalyzed Enantioselective 1,4-Addition of Grignard Reagents to α,β-Unsaturated Carbonyl Compounds. J. Am. Chem. Soc. 2006, 128, 9103−9118. (b) Caprioli, F.; Lutz, M.; Meetsma, A.; Minnaard, A. J.; Harutyunyan, S. R. Structural Characterisation of Cu Complexes of Chiral Ferrocenyl Diphosphine Ligands. Synlett 2013, 24, 2419−2422. 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Soc. 2010, 132, 10592− 10608. (8) Effendy; Di Nicola, C.; Fianchini, M.; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A. H. The structural definition of adducts of stoichiometry MX:dppx (1:1) M = CuI, AgI, X = simple anion, dppx = Ph2P(CH2)xPPh2, x = 3−6. Inorg. Chim. Acta 2005, 358, 763−795. (9) (a) Deng, Y. H.; Yang, Y. L.; Yang, X. J. Crystal structure of diiodo-bis[(4R,5R)-trans-4,5-bis[(diphenylphosphinomethyl)- 2,2-dimethyl-1,3-dioxalane]dicopper(I), Cu2I2(C31H32O2P2)2. Z. Kristallogr. - New Cryst. Struct. 2006, 221, 316−318. (b) Li, J.-X.; Du, Z.-X.; An, H.-Q.; Zhou, J.; Dong, J.-X.; Wang, S.-R.; Zhu, B.-L.; Zhang, S.-M.; Wu, S.-H.; Huang, W.-P. Syntheses, crystal structures and fluorescent properties of R,R-DIOP based copper (I) and cadmium (II) complexes {R,R-DIOP = (4R,5R)-trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxalane}. J. Mol. Struct. 2009, 935, 161−166. 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Chiral 1,1’diphosphetanylferrocenes: New Ligands for Asymmetric Catalytic Hydrogenation of Itaconate Derivatives. Angew. Chem., Int. Ed. 2000, 39, 1981−1984. (15) Blaser, H.-U.; Brieden, W.; Pugin, B.; Spindler, F.; Studer, M.; Togni, A. Solvias Josiphos Ligands: from Discovery to Technical Applications. Top. Catal. 2002, 19, 3−16. (16) (a) Wada, R.; Oisaki, K.; Kanai, M.; Shibasaki, M. Catalytic Enantioselective Allylboration of Ketones. J. Am. Chem. Soc. 2004, 126, 8910−8911. (b) Wada, R.; Shibuguchi, T.; Makino, S.; Oisaki, K.; Kanai, M.; Shibasaki, M. Catalytic Enantioselective Allylation of Ketoimines. J. Am. Chem. Soc. 2006, 128, 7687−7691. (c) Kanai, M.; ASSOCIATED CONTENT S Supporting Information * The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b01562. UV−vis spectra of 1−4, photographs of emissive PMMA films of 1−3, NMR spectra, X-ray crystallographic details, and computational results (PDF) Accession Codes CCDC 1555180−1555186 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033. ■ AUTHOR INFORMATION Corresponding Author *E-mail: glueck@dartmouth.edu. ORCID Russell P. Hughes: 0000-0002-1891-6530 David S. Glueck: 0000-0002-8438-8166 A. Timothy Royappa: 0000-0001-9935-8528 Howard H. Patterson: 0000-0001-9965-2057 Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ■ ACKNOWLEDGMENTS We thank the National Science Foundation (Grants CHE126578 and CHE-1562037) for support of this research at Dartmouth College, Robert Ditchfield for useful and enlightening conversations, Hai Qian and Ivan Aprahamian for help with quantum-yield measurements, and Alyson Michael and Joseph BelBruno for assistance with spin-coating. ■ REFERENCES (1) Recent examples: (a) Kainz, Q. M.; Matier, C. D.; Bartoszewicz, A.; Zultanski, S. L.; Peters, J. C.; Fu, G. C. Asymmetric coppercatalyzed C-N cross-couplings induced by visible light. Science 2016, 351, 681−684. (b) Jumde, R. P.; Lanza, F.; Veenstra, M. J.; Harutyunyan, S. R. Catalytic asymmetric addition of Grignard reagents to alkenyl-substituted aromatic N-heterocycles. Science 2016, 352, 433−437. (c) Iwamoto, H.; Kubota, K.; Ito, H. Highly selective Markovnikov hydroboration of alkyl-substituted terminal alkenes with a phosphine-copper(I) catalyst. Chem. 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Article pubs.acs.org/IC Cite This: Inorg. Chem. 2017, 56, 12809-12820 Synthesis, Structure, and Luminescence of Copper(I) Halide Complexes of Chiral Bis(phosphines) Sarah K. Gibbons,† Russell P. Hughes,† David S. Glueck,*,† A. Timothy Royappa,‡ Arnold L. Rheingold,‡ Robert B. Arthur,§ Aaron D. Nicholas,§ and Howard H. Patterson§ † 6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States Department of Chemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States § Department of Chemistry, University of Maine, Orono, Maine 04469, United States Downloaded via TEXAS WOMAN'S UNIV on December 9, 2018 at 04:16:49 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. ‡ S Supporting Information * ABSTRACT: For investigation of structure−property relationships in copper phosphine halide complexes, treatment of copper(I) halides with chiral bis(phosphines) gave dinuclear [Cu((R,R)-i-Pr-DuPhos)(μ-X)]2 [X = I (1), Br (2), Cl (3)], [Cu(μ-((R,R)-Me-FerroLANE)(μ-I)]2 (5), and [Cu((S,S)-Et-FerroTANE)(I)]2 (6), pentanuclear cluster Cu5I5((S,S)-EtFerroTANE)3 (7), and the monomeric Josiphos complexes Cu((R,S)CyPF-t-Bu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9); 1−3, 5, and 7−9 were structurally characterized by X-ray crystallography. Treatment of iodide 1 with AgF gave [Cu((R,R)-i-Pr-DuPhos)(μ-F)]2 (4). DuPhos complexes 1− 4 emitted yellow-green light upon UV irradiation at room temperature in the solid state. This process was studied by low-temperature emission spectroscopy and density functional theory (DFT) calculations, which assigned the luminescence to (M + X)LCT (Cu2X2 to DuPhos aryl) excited states. Including Grimme’s dispersion corrections in the DFT calculations (B3LYP-D3) gave significantly shorter Cu−Cu distances than those obtained using B3LYP, with the nondispersion-corrected calculations better matching the crystallographic data; other intramolecular metrics are better reproduced using B3LYP-D3. A discussion of the factors leading to this unusual observation is presented. ■ INTRODUCTION Copper(I) phosphine halide complexes are common precursors in catalysis,1 and their luminescent properties have often been investigated.2 For both applications, varying the phosphine enables rational control of the structure and properties of the copper complex. For example, the structure of [Cu(diphos)(X)]n (X = halide) depends on the chelating bis(phosphine) diphos (Chart 1). Three-coordinate monomers A are known for bulky chelates, such as Cu(dapBz)(I),3 or for ligands with large bite angles, as in Cu(Josiphos)(Br) (R = Cy, R′ = Ph; Chart 1).4 Fourcoordinate dimers B, with approximately tetrahedral copper, chelating bis(phosphines), and bridging halides, are the most common, with ligands such as dppf,5 dppBz,6 Binap,7 and dppp.8 Finally, four-coordinate dimers C, with both halides and bis(phosphines) bridging, are often observed with flexible ligands having larger bite angles, as in [Cu(μ-diop)(μ-X)]2 (X = Cl, I)9 or CuI complexes of dppb and dppPent.10 The free energies of the isomers A−C are often similar (Chart 1), so mixtures of isomers and interconversion between them can be observed. For example, both monomeric and dimeric [Cu(Josiphos)(Br)]n could be isolated in pure form; they underwent solvent-dependent interconversion.4 Similarly, both structures B and C were observed in the same crystal for © 2017 American Chemical Society Chart 1. Structures of [Cu(diphos)(X)]n Complexes [Cu(Ph-BPE)(Cl)]2.11 Small changes may determine the observed structure; replacing PPh2 groups in dppBz with P(oTol)2 donors resulted in a change from dimer B to monomer A,3,6 while extending the linker between PPh2 donors by one Received: June 19, 2017 Published: October 24, 2017 12809 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Scheme 1. Synthesis of Complexes 1−9 Figure 1. ORTEP diagrams of 1·Et2O (left), 2·THF (middle), and 3·THF (right). The solvent molecules are not shown. CH2 group (dppp → dppb) switched diphos from a chelate in B to a bridging ligand in C.8,10 Luminescent properties have been reported for complexes of all three structure types, including Cu(dapBz)(I) (A),3 [Cu(Binap)(I)]2 (B),12 and [Cu(μ-diop)(μ-Cl)]2 (C).9b Changing the halide and/or the bis(phosphine) caused changes of the emission color and quantum yield; the resulting structure−property relationships are potentially valuable in the design and synthesis of new emitters with tailored photophysical properties.2 With this background, we report here the synthesis, structure, and luminescent properties of new copper halide complexes with the chiral bis(phospholanes) i-Pr-DuPhos and MeFerroLANE,13 the analogous chiral bis(phosphetane) EtFerroTANE,14 and the P(t-Bu)2-substituted Josiphos ligands CyPF-t-Bu and PPF-t-Bu (Scheme 1).15 In earlier work, Cu(iPr-DuPhos) complexes were formed in situ and used as precursors in asymmetric catalysis, but these starting materials were not isolated and their structures were not determined.16 In contrast, the ferrocene-based Me-FerroLANE, Et-FerroTANE, and t-Bu-Josiphos derivatives, with larger bite angles, have not yet been used in the preparation of copper complexes or in copper-catalyzed reactions. Besides providing structural in- formation for catalysis, we hoped to investigate structure− property relationships in luminescence by comparing the phospholane/phosphetane/dialkylphosphino donors to the more commonly used PAr2 groups shown in Chart 1. ■ RESULTS AND DISCUSSION Synthesis and Structure of Cu(diphos*) Halide Complexes. Treatment of copper halides with (R,R)-i-PrDuPhos gave the dimers [Cu((R,R)-i-Pr-DuPhos)(X)]2 [X = I (1), Br (2), Cl (3)] as light-yellow solids (Scheme 1). The analogous fluoride 417 was prepared from iodide 1 and AgF.18 Similar reactions of CuI with (R,R)-Me-FerroLANE and (S,S)Et-FerroTANE yielded orange [Cu((R,R)-Me-FerroLANE)(I)]2 (5) and [Cu((S,S)-Et-FerroTANE)(I)]2 (6), respectively. The cluster Cu5I5((S,S)-Et-FerroTANE)3 (7), which was originally observed as a byproduct in the synthesis of 6, was prepared rationally using a 5:3 ratio of CuI and the ligand. Finally, CuI and t-Bu-Josiphos ligands gave Cu((R,S)-CyPF-tBu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9) as red-orange crystals. With Me-FerroLANE and Et-FerroTANE, these syntheses also gave small amounts of phosphine oxides, presumably via oxidation by copper(II) impurities in CuI; similar observations 12810 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry were made with Me-DuPhos earlier.19 Using commercially available higher-purity CuI avoided this problem for the MeFerroLANE complex 5, but we were not able to obtain pure bulk samples of Et-FerroTANE complexes 6 and 7 (see the Experimental Section for details). Complexes 1−9 were characterized spectroscopically (see below), by elemental analyses, and, for 1−3, 5 and 7−9, by Xray crystallography (Figures 1−4, Table 1, and the Supporting Information, SI). as were the P−Cu−P bite angles, but the DuPhos complexes featured larger X−Cu−X and Cu−X−Cu angles, associated with longer Cu−Cu distances. As in 1−3, the structures of 5 and 7 also contained distorted tetrahedral copper, supported by bridging bis(phosphines). In 5, the large P−Cu−P angle of 123.78(4)° was accompanied by a diamond-shaped Cu2I2 core including acute Cu−I−Cu angles (63.5°) and a Cu−Cu distance of 2.8694(9) Å. Similar bridging coordination in copper complexes is known for dppf20 and its P(t-Bu)2 analogue dtbpf21 but was not previously reported with any metal for Me-FerroLANE. The structure of cluster 7 featured both a chelate Et-FerroTANE [bite angle = 112.5(3)°] and two bis(phosphetanes) bridging two coppers, with an unusual Cu5I5 core (Figure 3).22 As with Me-FerroLANE in 5, bridging coordination of Et-FerroTANE had not been observed earlier. For the three different types of bridging iodides in 7, slightly longer Cu−I bonds were generally observed with larger iodide coordination numbers [for μ4-I3, Cu2−I = 2.769(2) Å and Cu3−I = 2.740 Å; for μ3-I2, Cu1−I = 2.675(2) Å, Cu2−I = 2.680(3) Å, and Cu3−I = 2.650(2) Å; for μ2-I1, Cu2−I = 2.660(3) Å and Cu3−I = 2.669(2) Å]. As described in the Introduction, Cu(Josiphos)(Br) complexes with PPh2 and PCy2 donors formed three-coordinate monomers or four-coordinate, bromide-bridged dimers.4 As expected, increasing the size of the phosphine [P(t-Bu)2] and the halide (iodide) yielded monomeric crystals of 8 and 9. Their structures (Figure 4) were similar to those of a related monomeric bromide complex, with distorted trigonal-planar coordination and Josiphos bite angles of 106.21(3)° and 103.62(7)°. As seen in Table 2, changing the phosphine substituents (t-Bu/Cy/Ph) and halide (I/Br) had only small effects on the structures. Copper complexes 1−9 are the first examples with these ligands. For future applications, it would be useful to determine their coordination modes spectroscopically, without recourse to X-ray crystallography. Therefore, we investigated their 31P{1H} NMR spectra, which all featured broad signals typical of copper phosphine complexes.23 Binding i-Pr-DuPhos to the copper halides resulted in 31P NMR coordination chemical shifts from δ −11.2 (free ligand)24 to −2.8 (F), −7.1 (Cl), −5.6 (Br), or −3.6 (I; all data in CDCl3). Shifts similar in magnitude were observed for the CuX complexes of the related o-phenylenelinked bis(phosphine) dppBz in 10−12, from δ −13.0 (ligand)25 to −17.2 (Cl), −19.0 (Br), and −22.1 (I).6 Similarly, the Me-FerroLANE 31P NMR chemical shift moved from δ −1.1 (ligand) to 3.5 (CDCl3) or −8.9 (C6D6) upon formation of 5. This surprisingly large, reversible, solvent-dependent chemical shift difference might arise from a structural change, for example, isomerization between bridging and chelate bis(phosphines), but we have no direct evidence for this possibility. The Et-FerroTANE 31P NMR signal26 moved from δ 13.1 to two broad signals at δ 2.9 and −0.5 (CD2Cl2) in 7, which, on the basis of their relative intensity, were assigned to chelating and bridging Et-FerroTANE, respectively. This assignment is consistent with the 31P NMR shift of [Cu(EtFerroTANE)(I)]2 (6; δ 4.7 in CD2Cl2), which likely contains a bridging bis(phosphine), as in 5. For chelating t-Bu-Josiphos ligands, large P(t-Bu)2 and small PCy2 or PPh2 coordination chemical shifts were observed, from δ 46.6 and −15.4 to δ 26.5 and −14.7 for CyPF-t-Bu in 8 and from δ 45.9 and −26.1 to δ 32.1 and −22.3 for PPF-t-Bu in 9.27 This chelation led to large increases in JPP from 16 to 154 Hz and from 50 to 160 Hz for 8 and 9, respectively. Figure 2. ORTEP diagram of 5. Figure 3. ORTEP diagram of 7, showing μ4-I3, μ3-I2, and μ2-I1, as well as chelating Et-FerroTANE (P1) and bridging Et-FerroTANE (P2/ P3). The isomorphous structures of complexes 1−3 contained the extensively investigated Cu2(μ-X)2 core,2 which here was puckered in a “butterfly” geometry with distorted tetrahedral coordination at copper. Unfortunately, we were not able to grow suitable crystals of the fluoride complex 4 for comparison, but its structure and those of 1−3 were investigated computationally (see below). Table 1 summarizes the X-ray crystallographic structural data for 1−3 in comparison to those for the dppBz analogues 10−12, which contain the same ophenylene linker but PPh2 donors in place of the phospholanyl groups.6 The Cu−X and Cu−P bond lengths were very similar, 12811 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Figure 4. ORTEP diagrams of 8 (left) and 9·CH2Cl2 (right) with the solvent molecules omitted. Table 1. Average Values of Selected Bond Lengths (Å) and Angles (deg) in [Cu(i-Pr-DuPhos)(X)]2 Dimers 1−3 and the dppBz Analogues 10−126 no. X Cu−X Cu−P P−Cu−P P−Cu−X X−Cu−X Cu−X−Cu Cu···Cu CuX2/Cu′X2 dihedral angle 1 2 3 I Br Cl 2.6423(9) 2.4895(7) 2.3649(14) 2.255(2) 2.2536(12) 2.2500(14) 91.77(7) 91.51(4) 91.55(5) 116.32(6) 118.08(6) 118.08(6) 101.45(3) 95.40(5) 95.40(5) 76.28(3) 82.09(5) 82.09(5) 3.264 3.208 3.106 154.61 154.50 154.65 10 11 12 I Br Cl 2.635(9) 2.478(7) 2.359(1) 2.281(2) 2.259(1) 2.254(2) 87.5(6) 89.2(4) 89.0(5) 114.24(6) 114.66(4) 116.38(6) 109.3(3) 107.6(2) 102.3(4) 66.7(2) 69.8(2) 74.8(4) 2.898 2.837 2.866 143.7 124.5 150.9 Table 2. Selected Bond Lengths (Å) and Angles (deg) in Cu(t-Bu-Josiphos)(I) Complexes 8 and 9 and the Analogous Bromide Complex Cu(PPF-t-Bu)(Br) Josiphos/X CyPF-t-Bu/ I (8) PPF-t-Bu/I (9· CH2Cl2) rac-PPFCy/Bra enant-PPFCy/Bra R/R′ Cu−X Cu−P1 Cu−P2 X−Cu−P1 X−Cu−P2 P1−Cu−P2 ref t-Bu/Cy 2.5187(4) 2.2437(8) 2.2562(8) 123.34(2) 130.41(2) 106.21(3) this work t-Bu/Ph 2.4970(9) 2.232(2) 2.2563(19) 126.16(6) 130.19(6) 103.62(7) this work Cy/Ph 2.3130(3) 2.2395(6) 2.2429(5) 130.20(2) 125.88(2) 102.51(2) 4b Cy/Ph 2.3232(5) 2.2659(7) 2.2626(8) 130.86(2) 126.69(2) 101.97(3) 4b Figure 5. UV−vis spectra of 1−4 in CH2Cl2 (10−4 M). 6). Emission also occurred in poly(methyl methacrylate) (PMMA) films formed by spin-coating of CH2Cl2 solutions (see the SI).29 In contrast, no emission was observed in ferrocene-based 5−9. a The structure of the bromide complex in ref 4b was determined separately with racemic and enantiomerically pure Josiphos ligands. All complexes in this work were prepared with enantiomerically pure ligands. Photophysical Properties of Complexes 1−4. As shown in Figure 5, varying the halide in DuPhos complexes 1−4 had little effect on their UV−vis spectra in CH2Cl2.28 For 1−3, the intense peaks around 360 nm had extinction coefficients of ∼104 M−1, consistent with their assignment, as in similar complexes, to (M + X)LCT charge-transfer processes.6 Solid samples of the DuPhos complexes 1−4 emitted yellowgreen light upon UV irradiation at room temperature (Figure Figure 6. Samples of 1−4 at room temperature under ambient light (above) and upon UV irradiation (below). 12812 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry The luminescence of 1−4 was further probed by lowtemperature spectroscopy (Figure 7 and Table 3). The Table 4. Comparison of the Gas-Phase Cu−Cu Distances and CuCl2Cu Bridge Fold Angles (Dihedral Angles between the CuCl2 Planes) As Calculated by DFT (B3LYP-D3 and B3LYP) and Determined Crystallographically in the Solid State Cu−Cu distance (Å) I (1) Br (2) Cl (3) F (4) CuCl2Cu fold angle (deg) B3LYP-D3 B3LYP X-ray B3LYP-D3 B3LYP X-ray 3.061 2.862 2.861 2.610 3.426 3.254 3.180 2.909 3.264 3.208 3.106 143.2 145.4 146.9 146.2 157.6 164.4 162.4 168.9 154.6 154.5 154.7 Figure 7. Luminescence spectra of 1−4 at 77 K. All emission spectra were obtained using 400 nm as the excitation wavelength. All excitation spectra were obtained using the emission peak maximum. Table 3. Photophysical Data for 1−4 (Solid State, 77 K) compound (X) 1 2 3 4 (I) (Br) (Cl) (F) λex (nm)a λem (nm) apparent Stokes shift (cm−1)b quantum yield (298 K) 397 372 374 384 532 549 542 539 6390 8670 8290 7490 0.039(3) 0.017(2) <0.01 <0.01 Figure 8. DFT-calculated gas-phase structures for 3 using the B3LYPD3 (blue) and B3LYP (bronze) functionals, looking down the Cl−Cl vector. λmax from the excitation spectrum. Energy difference between the absorption and emission peaks, which may not involve the same excited state. a b between each Cl−Cu−Cl plane is significantly larger and the Cu−Cu distance significantly longer than when dispersion corrections are included; analogous trends were observed for the iodide, bromide, and fluoride analogues, although no crystallographic data are available for the fluoride. Thus, the dispersion-corrected functional underestimates the fold angle in the bridge, with a resultant large decrease in the Cu−Cu distance. We suggest that, in the gas-phase calculation, in which no intermolecular interactions are included, many small intramolecular dispersion attractions between the ligand C−H bonds are sufficient to cause additional folding in the bridge and reduction in the Cu−Cu distance, as shown in Figure 8, while in the solid state, these intramolecular interactions are counterbalanced by intermolecular interactions to give a more planar bridge and a longer Cu−Cu distance. This illustrates that care must be used when validating the quality of gas-phase DFT results by their agreement, or lack thereof, with crystallographic data. We will have more to say about the solution structure later. As shown in Figure 9 for the chloro complex 3, the computed highest occupied molecular orbitals (HOMOs) in the halide series involve the interactions of Cu 3d, halide p, and out-of-phase P lone-pair combinations, and the lowest unoccupied molecular orbital (LUMO) is an entirely ligandbased π* molecular orbital within the i-Pr-DuPhos o-phenylene group. Time-dependent DFT (TD-DFT) methods were used to compute the UV−vis spectra of 1−4.29 There is reasonable agreement between the computed gas-phase spectra (Figure 10) and the experimental ones in CH2Cl2 solution. In excitation profiles in the solid state at 77 K, with λmax ranging from 372 to 397 nm, were similar to the room temperature UV−vis spectra in CH2Cl2 solution, except for the low-energy absorption observed in solution for the fluoride 4.28 Quantum yields measured for solid samples at room temperature in air are included in Table 3. Consistent with qualitative observations, the iodide complex 1 had the brightest emission under these conditions. Electronic Structure of Complexes 1−4: Computational Studies. To investigate the photophysical properties of DuPhos complexes 1−4, we calculated the structures of their ground and excited states using density functional theory (DFT) methods (see the Experimental Section and SI for details). For the ground states, the computed (gas-phase) structures were in reasonable agreement with those observed by X-ray crystallography in the solid state. The calculations slightly overestimated the Cu−X and Cu−P bond lengths, with the best agreement for functionals including a dispersion correction.30 However, structures optimized with the B3LYP-D3 functional, which includes dispersion corrections, showed significantly larger deviations from the crystallographic metrics within the Cu2X2 core, especially in the Cu···Cu distances; these core metrics were better reproduced by B3LYP calculations without dispersion (Table 4). This is an unusual deviation from current thinking, in which inclusion of dispersion is usually strongly advocated.30 A superimposition of structures of the chloride dimer 3 determined using both functionals is shown in Figure 8. As shown in Table 4, without dispersion corrections, the fold angle 12813 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry Figure 9. Calculated (B3LYP-D3) HOMO (left) and LUMO (right) for 3. consistent with weaker bonding in both the Cu2X2 core and the DuPhos arene ring. The superimposition also illustrates the significant twisting of the DuPhos ligand containing the long C−C bond relative to the ground state. Calculations without dispersion gave similar results but with less folded Cu2X2 cores, as was also observed for the ground states. Structure−Property Relationships in the Photophysical Properties of 1−4. As in structurally similar copper(I) phosphine halide complexes, we propose that excitation from a Cu2X2-based HOMO to a π*-acceptor phosphine LUMO (DuPhos o-phenylene group)6 in 1−4 leads to (M + X)LCT excited states, for which the structures of the lowest-energy singlet states were optimized. By analogy to previous work,6 we assume that the emissive excited states have (M + X)LCT character, but cannot tell if they are singlets or triplets. In related complexes, (M + X)LCT emission energy can often be tuned by changing the halide and/or phosphine to control the energy of the HOMO and/or LUMO.31 Table 5 compares low-temperature emission spectral data for 1−3 and analogous complexes, which all also contain P-aryl acceptor groups. Because related fluoride complexes are rare, data for 4 are not included. In some cases (numbers 2−4), emission wavelengths showed a smooth dependence on the halide, in the order Cl > Br > I. This behavior has been rationalized on the basis of the relative ligand-field strengths (Cl > Br > I), which make the Cu2X2 HOMO highest in energy for X = Cl, leading to reduced emission energy and higher wavelength.6,32,33 However, in some closely related structures, the halide had little effect (entries 5 and 6).34,35 Our data for 1−3, likewise, did not show a smooth trend (number 1; note that the emission maximum for fluoride 4 was at 539 nm). It has been proposed that such behavior reflects an important contribution from the phosphine donor orbitals to the HOMO.2a A more direct test of the effects of switching from the PPh2 donor to the phospholane group comes from comparing data for 1−3 with the dppBz analogues 10−12 (Table 5, entries 1 and 2). The ligand field of the alkylphosphine donor phospholane should be greater than that of the arylphosphine PPh2 group.36 This should increase the HOMO energy, reducing the emission energy and increasing the wavelength, as described above for the halides. This argument is consistent with the literature emission data for the phosphinopyridine Figure 10. Computed (B3LYP) UV−vis spectra of 1−4. particular, the calculations reproduced the similarity of the spectra and their lack of dependence on the halide. Notably, the analogous spectral calculations on the more folded B3LYP-D3 structures gave poorer agreement with experiment (see the SI), suggesting that the solution structures of these dimers may be more similar to the less folded solid-state ones, in which intramolecular dispersive forces are less controlling of the structure. Optimization of the first singlet excited state was also carried out for each compound using TD-DFT methods. An overlay of the computed structures of the ground and first excited states for chloride complex 3 (Figure 11) is consistent with the expected results of a HOMO−LUMO transition and an (M + X)LCT emissive excited state. In particular, the excited state included longer Cu−X and Cu···Cu distances, with a significantly longer C−C bond in one DuPhos aryl group, Figure 11. Overlay of the computed (B3LYP-D3) ground-state (red) and excited-state (blue) structures for 3. 12814 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry The synthesis and structural characterization of i-Pr-DuPhos complexes 1−3 established the expected chelation, which is consistent with previous hypotheses on the mechanisms of Cu(i-Pr-DuPhos)-catalyzed reactions.16 The larger bite angles of the ferrocene-linked bis(phospholane) Me-FerroLANE and bis(phosphetane) Et-FerroTANE resulted in different structures, with chelating and/or bridging coordination in 5 and 7. The combination of large bite angles, bulky phosphine substituents, and iodide ligands led to monomeric t-BuJosiphos complexes 8 and 9, as expected in comparison to related complexes.4 Related structure−property relationships were observed in the photophysical properties of emissive complexes 1−4, which contain the better donor phospholanes in comparison to analogues with the more commonly used diarylphosphino groups. As shown by the comparison in Table 5, however, varying the halide in the dimers [Cu(diphos)(X)]2 may result either in smooth trends in the emission energy or in discontinuities, as in our data for 1−4; further structure− property studies, including additional study of rare fluoride complexes, may enable better control of these parameters. We also observed that a better match of the Cu2X2 core crystal structure and the solution UV−vis spectra to computed results was obtained in DFT calculations when dispersion was not included, which may be more general in such conformationally flexible systems. Table 5. Emission Spectroscopic Data (nm) for 1−3 and Related [Cu(diphos)(X)]2 Complexesa ■ a Data from solid-state emission spectra at 77 K, except for entry 6 (room temperature in CH2Cl2 solution). EXPERIMENTAL SECTION General Experimental Details. Unless otherwise noted, all reactions and manipulations were performed in dry glassware under a nitrogen atmosphere at ambient temperature in a glovebox or using standard Schlenk techniques. Pentane, CH2Cl2, ether, tetrahydrofuran (THF), and toluene were dried over alumina columns similar to those described by Grubbs et al.38 NMR spectra were recorded with 500 or 600 MHz Bruker spectrometers. 1H or 13C NMR chemical shifts are reported versus Me4Si and were determined by reference to the residual 1H or 13C solvent peaks. 31P NMR chemical shifts are reported versus H3PO4 (85%) used as an external reference. Coupling constants are reported in hertz, as absolute values. Unless indicated, peaks in the NMR spectra are singlets. Quantitative Technologies Inc./Intertek Pharmaceutical Services (Whitehouse, NJ) or Atlantic Microlab (Norcross, GA) provided elemental analyses. Mass spectrometry was performed at the University of Illinois. Reagents were from commercial suppliers. [Cu((R,R)-i-Pr-DuPhos)(I)]2 (1). To a slurry of copper(I) iodide (44 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-i-PrDuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting yellow solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of pale-yellow powder and yellow crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A pale-yellow crystalline solid formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.140 g, 99%). The solid was washed with pentane to remove a small amount of free i-Pr-DuPhos. A sample recrystallized from CH2Cl2 contained 0.75 equiv of that solvent, according to 1H NMR integration and elemental analysis. Anal. Calcd for C52H88Cu2I2P4·0.75CH2Cl2: C, 49.43; H, 7.04. Found: C, 49.74; H, 7.08. HRMS. Calcd for C52H88Cu2I2P4: m/z 1216.2518. Found: m/z 1216.2498. 31P{1H} NMR (CDCl3, 25 °C): δ −3.6. 1H NMR (CDCl3, 25 °C): δ 7.70−7.69 (m, 4H, Ar), 7.47−7.46 (m, 4H, Ar), 2.53−2.50 (br m, 4H, CH), 2.31−2.23 (br m, 8H, CH2), 2.20− 2.15 (br m, 4H, CH), 2.09−2.06 (br m, 4H, CH), 1.79−1.74 (overlapping m, 4H, CH2), 1.71−1.64 (br m, 4H, CH2), 1.26−1.22 (br m, 4H, CH), 1.11 (d, J = 7, 12H, i-Pr Me), 0.94 (d, J = 7, 12H, i-Pr Me), 0.75 (d, J = 7, 12H, i-Pr Me), 0.68 (d, J = 7, 12H, i-Pr Me). 13 C{1H} NMR (CDCl3, 25 °C): δ 143.6 (t, J = 21, quat Ar), 134.7 (t, J complexes in Chart 2 containing PPh2 and phospholane donors, a rare example of this comparison,37 and it also works Chart 2. Emission Wavelength Data (Solid State, Room Temperature) for Phosphinopyridine CuI Complexes Containing Diphenylphosphino or Phospholane Donors in rationalizing the increased emission wavelength for 1 and 2 in comparison to their dppBz analogues 10 and 11. The similar emission wavelengths for 3 and 12 may reflect overlaid halide effects. ■ CONCLUSIONS Structure−Property Relationships. As described in the Introduction (Chart 1), changing the bis(phosphine) controls the structure and properties of [Cu(diphos)(X)]n complexes, and we have observed similar relationships here with several chiral bis(phosphines) new to copper coordination chemistry. 12815 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry NMR (CDCl3, 25 °C): δ −2.8. 31P{1H} NMR (THF-d8, 25 °C): δ −6.2. 19F NMR (THF-d8, 25 °C): δ −140.3. 1H NMR (THF-d8, 25 °C): δ 7.82−7.80 (m, 4H, Ar), 7.48−7.46 (m, 4H, Ar), 2.62−2.56 (br m, 4H, CH), 2.32−2.19 (br m, 16H, overlapping CH2 and CH), 1.84 (apparent dq, J = 6, 4H, CH2), 1.79−1.70 (br m, 4H, CH2), 1.42 (very br, 4H, CH), 1.16 (d, J = 7, 12H, i-Pr Me), 0.96 (d, J = 8, 12H, i-Pr Me), 0.72 (d, J = 7, 12H, i-Pr Me), 0.68 (d, J = 6, 12H, i-Pr Me). 13 C{1H} NMR (THF-d8, 25 °C): δ 144.8 (t, J = 21, quat Ar), 135.4 (t, J = 3, CH), 130.1 (CH), 52.8 (t, J = 8, CH), 51.4 (t, J = 8, CH), 32.6 (CH2), 31.3 (t, J = 9, CH), 29.4 (CH), 29.1 (CH2), 25.0, (br, i-Pr Me), 24.2 (br, i-Pr Me), 21.1 (i-Pr Me), 20.9 (br, i-Pr Me). [Cu((R,R)-Me-FerroLANE)(I)]2 (5). Treatment of CuI with MeFerroLANE gave 5; the formation of impurities in this reaction depended on the solvent and the source/purity of copper iodide, as summarized below. To a slurry of CuI (Strem, 98%; 22 mg, 0.12 mmol) in 2 mL of THF was added a solution of (R,R)-Me-FerroLANE (37.5 mg, 0.12 mmol) in 2 mL of THF, and the resulting dark-orange solution was stirred for 20 min. The solution was concentrated under vacuum to give an orange solid. The solid was redissolved in THF; slow evaporation gave a mixture of orange crystals and amorphous material (0.058 g, 86%), which contained an unidentified impurity (31P{1H} NMR: δ 62.9). In a similar experiment, the orange solid was washed with ether and pentane; X-ray-quality crystals were obtained from the pale-orange pentane solution. No impurities were formed in a similar preparation in toluene, which gave orange crystals after recrystallization from toluene/pentane at −20 °C. Similarly, no impurities were observed with higher-purity CuI in THF. To a slurry of “Puratronic” CuI (Alfa Aesar, 99.999%; 22 mg, 0.12 mmol) in 1 mL of THF was added a solution of (R,R)-Me-FerroLANE (47.5 mg, 0.12 mmol) in 2 mL of THF. The resulting bright-orange solution was stirred for 20 min and then filtered through Celite. Concentration under vacuum gave an analytically pure orange powder (53 mg, 42% yield). Anal. Calcd for C44H64Cu2I2P4Fe2: C, 43.70; H, 5.33. Found: C, 43.51; H, 5.24. HRMS. Calcd for C44H64Cu2IP4Fe2 [(M − I)+]: m/z 1081.0294. Found: m/z 1081.0278. Because the 31P NMR spectra were solvent-dependent, we report NMR data in different solvents. 31 1 P{ H} NMR (CDCl3, 25 °C): δ 3.5. 31P{1H} NMR (C6D6, 25 °C): δ −8.9. 1H NMR (CDCl3, 25 °C): δ 4.55 (4H, Cp CH), 4.34 (overlapping, 8H, Cp CH), 4.20 (4H, Cp CH), 2.75−2.72 (br m, 4H, CH), 2.43−2.41 (br m, 4H, CH), 2.27−2.23 (br m, 4H, CH2), 2.02− 1.98 (br m, 4H, CH2), 1.62 (apparent q, J = 10, 12H, Me), 1.51−1.45 (br m, 4H, CH2), 1.34−1.30 (br m, 4H, CH2), 0.90 (apparent q, J = 7, Me). 1H NMR (C6D6, 25 °C): δ 4.66 (4H, Cp CH), 4.17 (4H, Cp CH), 3.97 (4H, Cp CH), 3.87 (4H, Cp CH), 2.83 (4H, CH), 2.51− 2.49 (br m, 4H, CH), 2.03 (4H, CH2), 1.93 (4H, CH2), 1.89 (apparent q, J = 8, 12H, Me), 1.51 (4H, CH2), 1.25−1.21 (br m, 4H, CH2), 1.19 (apparent q, J = 6, 12H, Me). All of the signals were broad. 13 C{1H} NMR (CDCl3, 25 °C): δ 76.4 (t, J = 12, Cp CH), 73.6 (br t, quat Cp), 73.3 (Cp CH), 71.1 (Cp CH), 70.5 (Cp CH), 36.0 (CH2), 35.6 (CH2), 34.9 (t, J = 9, CH), 34.0 (t, J = 9, CH), 20.9 (t, J = 9, Me), 14.9 (Me). 13C{1H} NMR (C6D6, 25 °C): δ 77.2 (t, J = 10, Cp CH), 75.4 (br t, quat C), 72.8 (Cp CH), 70.7 (Cp CH), 69.7 (Cp CH), 36.2 (CH2), 36.0 (t, J = 8, CH), 35.3 (CH2), 35.0 (t, J = 8, CH), 21.3 (t, J = 7, Me), 16.3 (Me). Cu2I2((S,S)-Et-FerroTANE)2 (6). As with the Me-FerroLANE analogue 5, impurities were formed in the reaction of Et-FerroTANE and CuI. Varying the solvent (THF or toluene) and/or the CuI purity (98% to 99.9999%) did not avoid this problem, and adding copper wire, to reduce putative copper(II) impurities,39 was also unsuccessful, so we were not able to get pure bulk samples of 6. In a typical synthesis, to a slurry of CuI (Strem, 98%; 44 mg, 0.23 mmol) in 2 mL of THF was added a solution of (S,S)-Et-FerroTANE (102 mg, 0.23 mmol) in 1 mL of THF. The resulting orange solution was stirred for 20 min and then concentrated under vacuum to give an orange solid (134 mg, 92%). 31P NMR spectra of the bulk solid (CD2Cl2) showed an impurity signal at 64.3 ppm (7%), which was present in all noncrystalline material. The 31P NMR spectrum of a portion of the original reaction mixture (THF) showed peaks due to the impurity (δ 61.2), plus additional signals at δ 56.7 (trace), 12.2 (Et-FerroTANE), = 2, CH), 129.8 (CH), 52.4 (t, J = 9, CH), 51.3 (t, J = 9, CH), 32.8 (CH2), 30.7 (t, J = 8, CH), 28.7 (CH), 28.3 (CH2), 24.9 (t, J = 3, i-Pr Me), 23.8 (t, J = 5, i-Pr Me), 21.5 (t, J = 3, i-Pr Me), 20.3 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(Br)]2 (2). To a slurry of copper(I) bromide (33 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-iPr-DuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting yellow solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of yellow powder and yellow crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A yellow crystalline solid was formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.126 g, 97%). X-ray crystallography showed that the crystals were 2·THF. Anal. Calcd for C52H88Cu2Br2P4: C, 55.56; H, 7.89. Found: C, 55.56; H, 8.05. HRMS. Calcd for C52H88Cu2Br2P4: m/z 1120.2795. Found: m/z 1120.2767. 31P{1H} NMR (CDCl3, 25 °C): δ −5.6. 1H NMR (CDCl3, 25 °C): δ 7.69 (br m, 4H, Ar), 7.46 (br m, 4H, Ar), 2.51 (br m, 4H, CH), 2.25 (br m, 8H, CH2), 2.13 (br m, 4H, CH), 2.03−2.02 (br m, 4H, CH), 1.79−1.74 (br m, 4H, CH2), 1.70−1.63 (br m, 4H, CH2), 1.2 (overlapping br m, 4H, CH), 1.1 (d, J = 7, 12H, i-Pr Me), 0.95 (d, J = 7, 12H, i-Pr Me), 0.77 (d, J = 6, 12H, i-Pr Me), 0.68 (d, J = 6, 12H, i-Pr Me). 13C{1H} NMR (CDCl3, 25 °C): δ 143.4 (t, J = 22, quat Ar), 134.6 (Ar), 129.7 (Ar), 52.4 (t, J = 9, CH), 51.5 (t, J = 8, CH), 33.0 (CH2), 30.8 (t, J = 9, CH), 28.7 (CH), 28.2 (CH2), 24.9 (br t, i-Pr Me), 23.7 (t, J = 5, i-Pr Me), 21.7 (br t, i-Pr Me), 19.7 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(Cl)]2 (3). To a slurry of copper(I) chloride (23 mg, 0.23 mmol) in 5 mL of THF was added a solution of (R,R)-iPr-DuPhos (96 mg, 0.23 mmol) in 2 mL of THF, and the resulting green solution was stirred for 20 min. The solution was concentrated under vacuum to give a mixture of yellow-green powder and yellowgreen crystalline material. The mixture was partially redissolved in ether (∼3 mL) at room temperature and then cooled to −20 °C. A yellow-green crystalline solid formed overnight. The solution was decanted, and the crystals were dried under vacuum (0.107 g, 89%). The solid was washed with pentane to remove a small amount of free i-Pr-DuPhos. X-ray crystallography showed that the crystals were 3· THF. The cocrystallized solvent molecules in dimers 1−3 appeared to be lost easily, according to elemental analyses. For a sample that was recrystallized from THF/ether, the 1H NMR spectrum showed that it contained about 1.5 equiv of THF, which was apparently lost before analysis. Anal. Calcd for C52H88Cu2Cl2P4: C, 60.34; H, 8.57. Found: C, 59.91; H, 8.53. Another sample, recrystallized from CH2Cl2, analyzed for a monosolvate. Anal. Calcd for C52H88Cu2Cl2P4·CH2Cl2: C, 56.83; H, 8.10. Found: C, 56.52; H, 8.08. After this solid had been stored at room temperature for several days, its 1H NMR spectrum showed the presence of 0.6 equiv of CH2Cl2. HRMS. Calcd for C52H88Cu2Cl2P4: m/z 1032.3806. Found: m/z 1032.3789. 31P{1H} NMR (CDCl3, 25 °C): δ −7.1. 1H NMR (CDCl3, 25 °C): δ 7.72−7.69 (br m, 4H, Ar), 7.48−7.47 (br m, 4H, Ar), 2.55−2.50 (br m, 4H, CH), 2.29−2.23 (br m, 8H, CH2), 2.19−2.12 (br m, 4H, CH), 2.06−2.02 (br m, 4H, CH), 1.81−1.75 (apparent dq, 1JH−H = 13, 2JH−H = 13, 4H, CH2), 1.71−1.64 (apparent dq, 1JH−H = 12, 2JH−H = 12, 4H, CH2), 1.24−1.21 (br m, 4H, CH), 1.12 (d, J = 7, 12H, i-Pr Me), 0.97 (d, J = 7, 12H, i-Pr Me), 0.80 (d, J = 7, 12H, i-Pr Me), 0.71 (d, J = 7, 12H, i-Pr Me). 13C{1H} NMR (CDCl3, 25 °C): δ 143.4 (t, J = 22, quat Ar), 134.6 (Ar), 129.7 (Ar), 52.6 (t, J = 10, CH), 51.6 (t, J = 11, CH), 33.2 (CH2), 30.9 (t, J = 9, CH), 28.9 (CH), 28.3 (CH2), 25.0 (t, J = 3, i-Pr Me), 23.7 (t, J = 6, iPr Me), 21.8 (t, J = 7, i-Pr Me), 19.6 (t, J = 4, i-Pr Me). [Cu((R,R)-i-Pr-DuPhos)(F)]2 (4). A solution of 1 (140 mg, 0.115 mmol) in 2 mL of THF was added to AgF (58 mg, 0.45 mmol, 2.0 equiv). The resulting slurry was protected from light and sonicated for 1.5 h in an ultrasonic cleaning bath, then filtered through Celite to remove precipitate formed during the reaction. The solvent was removed under vacuum to give a yellow-gold solid (74 mg, 64%). The parent ion was not observed in the mass spectrum, in which the main peak was a [Cu2(i-Pr-DuPhos)2] fragment. MS. Calcd for C52H88Cu2 [(MH − 2F)+]: m/z 963.4. Found: m/z 963.5. 31P{1H} 12816 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry 103%). Recrystallization from CH2Cl2/pentane at −20 °C gave orange crystals, which X-ray crystallography showed were 9·CH2Cl2. Elemental analysis showed that another batch of crystals contained 0.5 equiv of CH2Cl2. Anal. Calcd for C32H40CuFeIP2(CH2Cl2)0.5: C, 50.34; H, 5.33. Found: C, 50.42; H, 5.43. HRMS. Calcd for C32H40CuFeP2 [(M − I)+]: m/z 605.1251. Found: m/z 605.1258. 31P{1H} NMR (CH2Cl2, 25 °C): δ 32.1 (d, J = 160, P(t-Bu)2), −22.3 (d, J = 160, PPh2). 1H NMR (CDCl3, 25 °C): δ 8.07−8.04 (t, J = 8, 2H, Ar), 7.73 (t, J = 10, 2H, Ar), 7.49−7.46 (br m, 3H, Ar), 7.40−7.39 (br m, 3H, Ar), 4.58 (1H, Cp), 4.39 (1H, Cp), 4.08 (1H, Cp), 4.04 (5H, Cp), 3.47−3.46 (br m, 1H, CHMe), 1.99 (t, J = 7, 3H, CHMe), 1.37 (d, J = 13, 9H, tBu), 1.17 (d, J = 13, 9H, t-Bu). 13C{1H} NMR (CDCl3, 25 °C): δ 135.4 (d, J = 26, quat Ar), 134.4 (d, J = 15, Ar CH), 134.1 (d, J = 16, Ar CH), 133.2 (dd, J = 26, 9, quat Ar), 130.2 (Ar CH), 130.1 (Ar CH), 128.8 (d, J = 3, Ar CH), 128.7 (d, J = 2, Ar CH), 94.5 (dd, J = 20, 7, quat Cp), 75.9 (d, J = 24, quat Cp), 74.8 (d, J = 4, Cp CH), 71.0 (d, J = 8, Cp CH), 70.4 (Cp CH), 68.9 (d, J = 6, Cp CH), 37.2 (d, J = 4, CMe3), 35.3 (d, J = 5, CMe3), 33.0 (CHMe), 31.8 (d, J = 7, CMe3), 31.2 (d, J = 7, CMe3), 17.4 (d, J = 5, CHMe). UV−Vis Spectroscopy. UV−vis spectra were recorded on 10−4 M CH2Cl2 solutions of complexes 1−4 in a quartz cuvette at 298 K, using a Jasco V-630 spectrophotometer. Emission Spectroscopy. Luminescence spectra were collected for microcrystalline samples 1−4. Steady-state luminescence scans were run at 77 K. Liquid nitrogen was used as the coolant. Spectra were taken with a Quantamaster-1046 photoluminescence spectrophotometer from Photon Technology International. This spectrometer uses a 75 W xenon arc lamp combined with two excitation monochromators and one emission monochromator. A photomultiplier tube at 800 V was used as the emission detector. The solid samples were mounted on a copper plate using nonemitting copper-dust high-vacuum grease. All scans were run under vacuum using a Janis ST-100 optical cryostat. Solid-State Quantum-Yield Measurements. Solid-state spectra were collected for microcrystalline samples 1−4 in air at 298 K using a Horiba PTI QM-400 spectrometer equipped with an integrating sphere. The excitation wavelength for all samples was 400 nm. Luminescence of 1−3 in PMMA Thin Films. A 5% (w/w) solution of 1 (0.03 g) in 0.4 mL of CH2Cl2 was added to PMMA (0.03 g, atactic beads, average molecular weight = 350000; Polysciences), and the mixture was stirred overnight. A total of 400 μL of the paleyellow solution were pipetted onto a glass slide and spin-coated at 800 rpm for 30 s. The resulting thin film was luminescent under UV light (see the SI for photographs). The procedure was similar for the chloride and bromide analogues 2 and 3, which formed pale-green and yellow-green solutions, respectively. DFT Calculations. For comparison, DFT calculations were carried out at both the University of Maine and Dartmouth College, with different basis sets. At Maine, calculations were performed on complexes 1−3 with the Gaussian09 program hosted by the University of Maine Advanced Computing Group. All calculations were performed with the B3LYP exchange correlation and the LANL2DZ basis set throughout. Experimental XRD geometries of 1−3 were used as the initial input structures for ground-state optimization calculations. Optimized ground-state structures were used for vertical energy calculations using the TD-DFT method. Molecular orbitals were reproduced using Avogadro 1.1.1. At Dartmouth, calculations were carried out using the hybrid B3LYP functional (both with and without the zero-damping, twobody-only D3 correction of Grimme et al.; see the text)40 and the LACV3P** basis set, which uses Los Alamos core potentials for the Cu atom41 and the 6-311G** basis for all lighter atoms,42 as implemented in the Jaguar suite of programs.43 Computed groundstate structures were confirmed as energy minima by calculating the vibrational frequencies using second derivative analytical methods and confirming the absence of imaginary frequencies. Geometries of first singlet excited states were optimized using TD-DFT calculations, as implemented in the Jaguar program. UV−vis spectra were also calculated at the B3LYP ground-state geometries using TD-DFT, with unrestricted occupations and including 48 excited states. and 3.3 (6). Slow evaporation of this solution gave orange crystals, which X-ray crystallography showed were Cu5I5((S,S)-Et-FerroTANE)3 (7). HRMS. Calcd for C48H72Cu2IP4Fe2 [(M − I)+]: m/z 1137.0920. Found: m/z 1137.0925. 31P{1H} NMR (CD2Cl2, 25 °C): δ 4.7 (6), 12.1 (free Et-FerroTANE, 5%), and unidentified signals at δ 64.3 (7%), 59.2 (trace), and 45.4 (trace). 1H NMR (CD2Cl2, 25 °C): δ 4.53 (4H, Cp CH), 4.41 (8H, Cp CH), 4.36 (4H, Cp CH), 2.64 (4H, FerroTANE CH), 2.43−2.37 (br m, 12H, CH2 and FerroTANE CH), 2.27−2.24 (br m, 4H, CH2), 2.00−1.95 (br m, 4H, CH2), 1.38−1.37 (br m, 4H, CH2), 1.10 (t, J = 7, 12H, Me), 0.76 (t, J = 8, 12 H, Me). 13 C{1H} NMR (CD2Cl2, 25 °C): δ 77.1 (t, J = 11, Cp), 74.5−74.4 (br m, quat C), 73.7 (Cp), 71.6 (Cp), 70.5 (Cp), 35.4 (t, J = 15, FerroTANE CH), 35.1 (t, J = 14, FerroTANE CH), 34.4 (t, J = 5, CH2), 27.0 (t, J = 6, CH2), 25.2 (CH2), 14.0 (t, J = 6, Me), 12.3 (t, J = 4, Me). Cu5I5((S,S)-Et-FerroTANE)3 (7). To a slurry of CuI (Strem, 98%; 44 mg, 0.23 mmol, 5 equiv) in 2 mL of THF was added a solution of (S,S)-Et-FerroTANE (60 mg, 0.14 mmol, 3 equiv) in 1 mL of THF, and the resulting solution was stirred for 20 min. The resulting orange solution was concentrated under vacuum to yield a bright-orange solid (98 mg, 92%). 31P NMR spectra of the bulk solid showed an impurity at δ 64.6 (4.8%), which was present in all noncrystalline material. A portion of the solid was redissolved in THF; slow evaporation gave orange crystals of 7, identified by X-ray crystallography. As with 6, varying the CuI purity and the solvent (THF or toluene) did not prevent impurity formation, and we could not isolate pure bulk samples of 7. 31 1 P{ H} NMR (CDCl3, 25 °C): δ 1.8 to −1.1 (br m, FerroTANE). 31 1 P{ H} NMR (CD2Cl2, 25 °C): δ 2.9 (br, chelating FerroTANE), −0.5 (br, bridging FerroTANE). 1H NMR (CD2Cl2, 25 °C): δ 5.11− 5.03 (br m, 4H, Cp), 4.91−4.86 (br m, 4H, Cp), 4.64−4.52 (br m, 16 H, Cp), 2.78 (4H, FerroTANE CH), 2.48 (overlapping, 4H, FerroTANE CH), 2.41 (overlapping, 8H, CH2 and FerroTANE CH), 2.12−1.92 (br m, 8H, CH2), 1.93−1.92 (br m, 8H, CH2), 1.25− 1.22 (br m, 12H, CH2), 1.06−1.02 (br m, 18H, Me), 0.70−0.67 (t, J = 7, 18H, Me). 13C{1H} NMR (CD2Cl2, 25 °C): δ 78.6−78.2 (br m, Cp), 72.7−72.2 (br m, Cp), 71.7 (br, Cp), 35.8 (d, J = 32, FerroTANE CH), 34.9 (d, J = 13, FerroTANE CH), 30.1 (d, J = 12, FerroTANE CH), 27.1−27.0 (br m, CH2), 25.2−25.1 (br m, CH2), 22.5 (Me), 13.8 (br, Me), 13.6 (br, Me), 12.5 (Me), 12.4 (d, J = 6, Me). Cu((R,S)-CyPF-t-Bu)(I) (8). To “Puratronic” copper(I) iodide (Alfa Aesar, 99.999%, 22 mg, 0.12 mmol) was added a solution of (R,S)CyPF-t-Bu (67 mg, 0.12 mmol) in 2 mL of CH2Cl2. The resulting solution was stirred for 10 min and then concentrated under vacuum to give an orange solid, which contained residual solvent (105 mg, 117%). Recrystallization from CH2Cl2/pentane at −20 °C gave orange crystals, which X-ray crystallography showed were 8. Anal. Calcd for C32H52FeP2CuI: C, 51.59; H, 7.04. Found: C, 51.69; H, 7.01. HRMS. Calcd for C32H52FeP2CuI: m/z 744.1234. Found: m/ z 744.1235. 31P{1H} NMR (CH2Cl2, 25 °C): δ 26.5 (d, J = 154, P(tBu)2), −14.7 (d, J = 154, PCy2). 1H NMR (CDCl3, 25 °C): δ 4.50 (1H, Cp), 4.37 (2H, Cp), 4.20 (5H, Cp), 3.18 (br, 1H, CHMe), 2.19− 2.11 (m, 4H, Cy CH and CH2), 1.95 (t, J = 7, 3H, CHMe), 1.89−1.63 (m, 10H, Cy CH2), 1.45 (d, J = 13, 9H, t-Bu), 1.39−1.30 (m, 6H, Cy CH2), 1.23−1.15 (m, 2H, Cy CH2), 1.03 (d, J = 13, 9H, t-Bu). 13 C{1H} NMR (CDCl3, 25 °C): δ 94.7 (dd, J = 14, 6, quat Cp), 74.7 (d, J = 14, quat Cp), 73.7 (Cp CH), 70.2 (d, J = 7, Cp CH), 69.7 (Cp CH), 68.0 (d, J = 4, Cp CH), 38.5 (d, J = 14, Cy CH), 37.1 (d, J = 3, CMe3), 35.1 (d, J = 6, CMe3), 33.8−33.7 (dd, J = 14, 7, Cy CH), 33.3 (CHMe), 31.2 (CMe3), 31.1 (CMe3), 30.9 (d, J = 10, Cy CH2), 29.2 (d, J = 5, Cy CH2), 28.6 (d, J = 5, Cy CH2), 27.6 (2 Cy CH2), 27.5 (d, J = 14, Cy CH2), 27.2 (d, J = 12, Cy CH2), 27.0 (d, J = 12, Cy CH2), 26.8 (d, J = 9, Cy CH2), 26.0 (d, J = 12, Cy CH2), 17.5 (d, J = 4, CHMe). Cu((R,S)-PPF-t-Bu)(I) (9). To “Puratronic” copper(I) iodide (Alfa Aesar, 99.999%, 22 mg, 0.12 mmol) was added a solution of (R,S)PPF-t-Bu (65 mg, 0.12 mmol) in 2 mL of CH2Cl2. The resulting solution was stirred for 10 min and then concentrated under vacuum to give an orange solid, which contained residual solvent (101 mg, 12817 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry ■ light-emitting diodes that exhibit delayed fluorescence. Dalton Trans. 2015, 44, 8369−8378. (4) (a) Harutyunyan, S. R.; López, F.; Browne, W. R.; Correa, A.; Peña, D.; Badorrey, R.; Meetsma, A.; Minnaard, A. J.; Feringa, B. L. On the Mechanism of the Copper-Catalyzed Enantioselective 1,4-Addition of Grignard Reagents to α,β-Unsaturated Carbonyl Compounds. J. Am. Chem. Soc. 2006, 128, 9103−9118. (b) Caprioli, F.; Lutz, M.; Meetsma, A.; Minnaard, A. J.; Harutyunyan, S. R. Structural Characterisation of Cu Complexes of Chiral Ferrocenyl Diphosphine Ligands. Synlett 2013, 24, 2419−2422. 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Soc. 2010, 132, 10592− 10608. (8) Effendy; Di Nicola, C.; Fianchini, M.; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A. H. The structural definition of adducts of stoichiometry MX:dppx (1:1) M = CuI, AgI, X = simple anion, dppx = Ph2P(CH2)xPPh2, x = 3−6. Inorg. Chim. Acta 2005, 358, 763−795. (9) (a) Deng, Y. H.; Yang, Y. L.; Yang, X. J. Crystal structure of diiodo-bis[(4R,5R)-trans-4,5-bis[(diphenylphosphinomethyl)- 2,2-dimethyl-1,3-dioxalane]dicopper(I), Cu2I2(C31H32O2P2)2. Z. Kristallogr. - New Cryst. Struct. 2006, 221, 316−318. (b) Li, J.-X.; Du, Z.-X.; An, H.-Q.; Zhou, J.; Dong, J.-X.; Wang, S.-R.; Zhu, B.-L.; Zhang, S.-M.; Wu, S.-H.; Huang, W.-P. Syntheses, crystal structures and fluorescent properties of R,R-DIOP based copper (I) and cadmium (II) complexes {R,R-DIOP = (4R,5R)-trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxalane}. J. Mol. Struct. 2009, 935, 161−166. (10) Zhang, X.; Song, L.; Hong, M.; Shi, H.; Xu, K.; Lin, Q.; Zhao, Y.; Tian, Y.; Sun, J.; Shu, K.; Chai, W. Luminescent dinuclear copper(I) halide complexes double bridged by diphosphine ligands: Synthesis, structure characterization, properties and TD-DFT calculations. Polyhedron 2014, 81, 687−694. (11) Yazaki, R.; Kumagai, N.; Shibasaki, M. Direct Catalytic Asymmetric Addition of Allyl Cyanide to Ketones via Soft Lewis Acid/Hard Bronsted Base/Hard Lewis Base Catalysis. J. Am. Chem. Soc. 2010, 132, 5522−5531. (12) Kunkely, H.; Pawlowski, V.; Vogler, A. Copper(I) Binap Complexes (binap = (2,2’-bis(diphenylphosphino)-1,1’-binaphthyl). Luminescence from IL and LLCT States. Inorg. Chem. Commun. 2008, 11, 1003−1005. (13) Burk, M. J.; Gross, M. F. New Chiral 1,1’-Bis(phospholano)ferrocene Ligands for Asymmetric Catalysis. Tetrahedron Lett. 1994, 35, 9363−9366. (14) Berens, U.; Burk, M. J.; Gerlach, A.; Hems, W. Chiral 1,1’diphosphetanylferrocenes: New Ligands for Asymmetric Catalytic Hydrogenation of Itaconate Derivatives. Angew. Chem., Int. Ed. 2000, 39, 1981−1984. (15) Blaser, H.-U.; Brieden, W.; Pugin, B.; Spindler, F.; Studer, M.; Togni, A. Solvias Josiphos Ligands: from Discovery to Technical Applications. Top. Catal. 2002, 19, 3−16. (16) (a) Wada, R.; Oisaki, K.; Kanai, M.; Shibasaki, M. Catalytic Enantioselective Allylboration of Ketones. J. Am. Chem. Soc. 2004, 126, 8910−8911. (b) Wada, R.; Shibuguchi, T.; Makino, S.; Oisaki, K.; Kanai, M.; Shibasaki, M. Catalytic Enantioselective Allylation of Ketoimines. J. Am. Chem. Soc. 2006, 128, 7687−7691. (c) Kanai, M.; ASSOCIATED CONTENT S Supporting Information * The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b01562. UV−vis spectra of 1−4, photographs of emissive PMMA films of 1−3, NMR spectra, X-ray crystallographic details, and computational results (PDF) Accession Codes CCDC 1555180−1555186 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033. ■ AUTHOR INFORMATION Corresponding Author *E-mail: glueck@dartmouth.edu. ORCID Russell P. Hughes: 0000-0002-1891-6530 David S. Glueck: 0000-0002-8438-8166 A. Timothy Royappa: 0000-0001-9935-8528 Howard H. Patterson: 0000-0001-9965-2057 Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. Notes The authors declare no competing financial interest. ■ ACKNOWLEDGMENTS We thank the National Science Foundation (Grants CHE126578 and CHE-1562037) for support of this research at Dartmouth College, Robert Ditchfield for useful and enlightening conversations, Hai Qian and Ivan Aprahamian for help with quantum-yield measurements, and Alyson Michael and Joseph BelBruno for assistance with spin-coating. ■ REFERENCES (1) Recent examples: (a) Kainz, Q. M.; Matier, C. D.; Bartoszewicz, A.; Zultanski, S. L.; Peters, J. C.; Fu, G. C. Asymmetric coppercatalyzed C-N cross-couplings induced by visible light. Science 2016, 351, 681−684. (b) Jumde, R. P.; Lanza, F.; Veenstra, M. J.; Harutyunyan, S. R. Catalytic asymmetric addition of Grignard reagents to alkenyl-substituted aromatic N-heterocycles. Science 2016, 352, 433−437. (c) Iwamoto, H.; Kubota, K.; Ito, H. Highly selective Markovnikov hydroboration of alkyl-substituted terminal alkenes with a phosphine-copper(I) catalyst. Chem. Commun. 2016, 52, 5916−5919. (2) (a) Tsuge, K.; Chishina, Y.; Hashiguchi, H.; Sasaki, Y.; Kato, M.; Ishizaka, S.; Kitamura, N. Luminescent copper(I) complexes with halogenido-bridged dimeric core. Coord. Chem. Rev. 2016, 306, 636− 651. (b) Peng, R.; Li, M.; Li, D. Copper(I) halides: A versatile family in coordination chemistry and crystal engineering. Coord. Chem. Rev. 2010, 254, 1−18. (c) Ford, P. C.; Cariati, E.; Bourassa, J. Photoluminescence Properties of Multinuclear Copper(I) Compounds. Chem. Rev. 1999, 99, 3625−3648. (3) (a) Hashimoto, M.; Igawa, S.; Yashima, M.; Kawata, I.; Hoshino, M.; Osawa, M. Highly Efficient Green Organic Light-Emitting Diodes Containing Luminescent Three-Coordinate Copper(I) Complexes. J. Am. Chem. Soc. 2011, 133, 10348−10351. (b) Osawa, M.; Hoshino, M.; Hashimoto, M.; Kawata, I.; Igawa, S.; Yashima, M. Application of three-coordinate copper(I) complexes with halide ligands in organic 12818 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. 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A Novel Easily Accessible Chiral Ferrocenyldiphosphine for Highly Enantioselective Hydrogenation, Allylic Alkylation, and Hydroboration Reactions. J. Am. Chem. Soc. 1994, 116, 4062−4066. This paper reports the 31P NMR chemical shift for PPF-t-Bu as 49.9 ppm, instead of the 45.9 ppm in ref (a). (c) Spindler, F. Ferrocenyldiphosphine als Liganden für Homogene Katalysatoren. Patent EP0612758A1 (Ciba-Geigy), 1994. (28) A reviewer pointed out that the low-energy absorption for the fluoride complex 4 was anomalous in comparison to 1−3. This feature was reproducible in samples from different batches of 4, and a similar peak around 450 nm is seen in the computed spectrum (see Figure 10). However, we have not been able to crystallize 4 to obtain it analytically pure, so this absorption might be due to impurities. Moreover, although 1−4 appeared to be readily soluble in these dilute (10−4 M) CH2Cl2 solutions, we cannot rule out the presence of colloids and light scattering from aggregates, which might give rise to this spectral absorption. Therefore, we have not included an extinction coefficient for 4. See the SI (Figure S1) for more information on the extinction coefficients. (29) Okano, Y.; Ohara, H.; Kobayashi, A.; Yoshida, M.; Kato, M. Systematic Introduction of Aromatic Rings to Diphosphine Ligands for Emission Color Tuning of Dinuclear Copper(I) Iodide Complexes. Inorg. Chem. 2016, 55, 5227−5236. (30) Grimme, S.; Hansen, A.; Brandenburg, J. G.; Bannwarth, C. Dispersion-Corrected Mean-Field Electronic Structure Methods. Chem. Rev. 2016, 116, 5105−5154. (31) Wallesch, M.; Volz, D.; Zink, D. M.; Schepers, U.; Nieger, M.; Baumann, T.; Bräse, S. Bright Coppertunities: Multinuclear CuI Complexes with N−P Ligands and Their Applications. Chem. - Eur. J. 2014, 20, 6578−6590. (32) Hong, X.; Wang, B.; Liu, L.; Zhong, X.-X.; Li, F.-B.; Wang, L.; Wong, W.-Y.; Qin, H.-M.; Lo, Y. H. Highly efficient blue−green neutral dinuclear copper(I) halide complexes containing bidentate phosphine ligands. J. Lumin. 2016, 180, 64−72. (33) Leitl, M. J.; Küchle, F.-R.; Mayer, H. A.; Wesemann, L.; Yersin, H. Brightly Blue and Green Emitting Cu(I) Dimers for Singlet Harvesting in OLEDs. J. Phys. Chem. A 2013, 117, 11823−11836. (34) Kang, L.; Chen, J.; Teng, T.; Chen, X.-L.; Yu, R.; Lu, C.-Z. Experimental and theoretical studies of highly emissive dinuclear Cu(I) halide complexes with delayed fluorescence. Dalton Trans. 2015, 44, 11649−11659. (35) Trivedi, M.; Nagarajan, R.; Kumar, A.; Rath, N. P.; Valerga, P. Synthesis, characterization, crystal structures and photophysical properties of copper(I) complexes containing 1,1’-bis(diphenylphosphino)ferrocene (B-dppf) in doubly-bridged mode. Inorg. Chim. Acta 2011, 376, 549−556. (36) (a) Cotton, F. A.; Faut, O. D.; Goodgame, D. M. L.; Holm, R. H. Magnetic Investigations of Spin-free Cobaltous Complexes. VI. Complexes Containing Phosphines and the Position of Phosphines in the Spectrochemical Series. J. Am. Chem. Soc. 1961, 83, 1780−1785. (b) Hughes, M.; Mason, J.; Leigh, G. J.; Richards, R. L. 95Mo studies of ligands relevant to dinitrogen fixation: NMR spectrochemical series based on 95Mo shielding. J. Organomet. Chem. 1988, 341, 381−389. (c) Thomas, G. Substitutionsreaktionen an Thiocyanatokomplexen. II. Absorptionsspektren der Tetra-isothiocyanato-diphosphino-chromate(III)-Stellung sec. und tert. Phosphine in der spektrochemischen Serie. Z. Anorg. Allg. Chem. 1968, 362, 191−204. (d) Bennett, M. A.; Clark, Wada, R.; Shibuguchi, T.; Shibasaki, M. Cu(I)-catalyzed asymmetric allylation of ketones and ketimines. Pure Appl. Chem. 2008, 80, 1055− 1062. (d) Zhong, C.; Kunii, S.; Kosaka, Y.; Sawamura, M.; Ito, H. Enantioselective Synthesis of trans-Aryl- and -Heteroaryl-Substituted Cyclopropylboronates by Copper(I)-Catalyzed Reactions of Allylic Phosphates with a Diboron Derivative. J. Am. Chem. Soc. 2010, 132, 11440−11442. (17) Heating 2 equiv of i-Pr-DuPhos and CuF2·2H2O in MeOH was proposed earlier (ref 16) to yield “Cu(i-Pr-DuPhos)(F)”, but no characterization data were reported. (18) For related copper fluorides, see: (a) Gurung, S. K.; Thapa, S.; Kafle, A.; Dickie, D. A.; Giri, R. Copper-Catalyzed Suzuki−Miyaura Coupling of Arylboronate Esters: Transmetalation with (PN)CuF and Identification of Intermediates. Org. Lett. 2014, 16, 1264−1267. (b) Gulliver, D. J.; Levason, W.; Webster, M. Coordination stabilised copper(I) fluoride. Crystal and molecular structure of fluorotris(triphenylphosphine)copper(I)•ethanol (1/2), Cu(PPh3)3•2EtOH. Inorg. Chim. Acta 1981, 52, 153−159. For use of AgF to make metal fluorides, see: (c) Martı ́nez-Prieto, L. M.; Melero, C.; del Rı ́o, D.; Palma, P.; Cámpora, J.; Á lvarez, E. Synthesis and Reactivity of Nickel and Palladium Fluoride Complexes with PCP Pincer Ligands. NMR-Based Assessment of Electron- Donating Properties of Fluoride and Other Monoanionic Ligands. Organometallics 2012, 31, 1425− 1438. (19) Côté, A.; Boezio, A. A.; Charette, A. B. Evidence for the Structure of the Enantioactive Ligand in the Phosphine-CopperCatalyzed Addition of Diorganozinc Reagents to Imines. Angew. Chem., Int. Ed. 2004, 43, 6525−6528. (20) (a) Pilloni, G.; Graziani, R.; Longato, B.; Corain, B. Synthesis and solution state of [(μ-dppf)(Cu(dppf))2]X2 (dppf= 1,1′-bis(diphenylphosphino)ferrocene; X = ClO4−, BF4−). Inorg. Chim. Acta 1991, 190, 165−167. (b) Díez, J.; Gamasa, M. P.; Gimeno, J.; Aguirre, A.; García-Granda, S.; Holubova, J.; Falvello, L. R. Novel Copper(I) Complexes Containing 1,1‘-Bis(diphenylphosphino)ferrocene (dppf) as a Chelate and Bridging Ligand: Synthesis of Tetrabridged Dicopper(I) Complexes [Cu2(μ-η1-C≡R)2(μ-dppf)2] and X-ray Crystal Structure of [Cu2(μ-η1-C≡CC6H4CH3-4)2(μ-dppf)2]. Organometallics 1999, 18, 662−669. (21) (a) Trivedi, M.; Singh, G.; Kumar, A.; Rath, N. P. A thiocyanatobridged copper(I) cubane complex and its application in palladiumcatalyzed Sonogashira coupling of aryl halides. Dalton Trans. 2013, 42, 12849−12852. (b) Trivedi, M.; Singh, G.; Kumar, A.; Rath, N. P. Syntheses, characterization, and structural studies of copper(I) complexes containing 1,1’-bis(di-tert-butylphosphino)ferrocene (dtbpf) and their application in palladium-catalyzed Sonogashira coupling of aryl halides. Dalton Trans. 2014, 43, 13620−13629. (c) Trivedi, M.; Singh, G.; Kumar, A.; Rath, N. P. 1,1’-Bis(di-tertbutylphosphino)ferrocene copper(I) complex catalyzed C-H activation and carboxylation of terminal alkynes. Dalton Trans. 2015, 44, 20874− 20882. (22) (a) Zhang, Y.; Wu, T.; Liu, R.; Dou, T.; Bu, X.; Feng, P. ThreeDimensional Photoluminescent Frameworks Constructed from SizeTunable CuI Clusters. Cryst. Growth Des. 2010, 10, 2047−2049. (b) Wu, T.; Li, M.; Li, D.; Huang, X.-C. Anionic CunIn Cluster-Based Architectures Induced by In Situ Generated N-Alkylated Cationic Triazolium Salts. Cryst. Growth Des. 2008, 8, 568−574. (c) Victoriano, L. I.; Garland, M. T.; Vega, A.; Lopez, C. Crystal and Molecular Structures of a Neutral Pentanuclear Copper(I)−Iodide Complex. Inorg. Chem. 1998, 37, 2060−2062. (d) Victoriano, L. I.; Garland, M. T.; Vega, A.; Lopez, C. Syntheses, properties, crystal and molecular structure of a novel neutral pentanuclear copper(I) iodide species. Copper(I) complexes with tetraethylthiuram monosulfide. J. Chem. Soc., Dalton Trans. 1998, 1127−1132. (23) Black, J. R.; Levason, W.; Spicer, M. D.; Webster, M. Synthesis and Solution Multinuclear Magnetic Resonance Studies of Homoleptic Copper(I) Complexes of Group 15 Donor Ligands. J. Chem. Soc., Dalton Trans. 1993, 3129−3136. (24) Burk, M. J.; Feaster, J. E.; Nugent, W. A.; Harlow, R. L. Preparation and Use of C2-Symmetric Bis(phospholanes): Production 12819 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820 Article Inorganic Chemistry R. J. H.; Goodwin, A. D. J. Electronic and Infrared Spectral Study of Chromium(III) Derivatives of the Type [Cr(NCS)4•(ligand)2]−. Inorg. Chem. 1967, 6, 1625−1631. (37) (a) For PPh2, see: Zink, D. M.; Bachle, M.; Baumann, T.; Nieger, M.; Kuhn, M.; Wang, C.; Klopper, W.; Monkowius, U.; Hofbeck, T.; Yersin, H.; Brase, S. Synthesis, Structure, and Characterization of Dinuclear Copper(I) Halide Complexes with P^N Ligands Featuring Exciting Photoluminescence Properties. Inorg. Chem. 2013, 52, 2292−2305. (b) For phospholane, see: Musina, E. I.; Shamsieva, A. V.; Strelnik, I. D.; Gerasimova, T. 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A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 2010, 132, 154104. (41) (a) Gaussian Basis Sets for Molecular Calculations: Dunning, T. H.; Hay, P. J. In Modern Theoretical Chemistry, Vol. 4: Applications of Electronic Structure Theory; Schaefer, H. F., III, Ed.; Plenum: New York, 1977. (b) Wadt, W. R.; Hay, P. J. Ab initio effective core potentials for molecular calculations. Potentials for main group elements Na to Bi. J. Chem. Phys. 1985, 82, 284−298. (c) Hay, P. J.; Wadt, W. R. Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals. J. Chem. Phys. 1985, 82, 299−310. (d) Hay, P. J.; Wadt, W. R. Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. J. Chem. Phys. 1985, 82, 270− 283. (42) (a) Frisch, M. J.; Pople, J. A.; Binkley, J. S. Self-consistent molecular orbital methods 25. Supplementary functions for Gaussian basis sets. J. Chem. Phys. 1984, 80, 3265−3269. (b) Clark, T.; Chandrasekhar, J.; Spitznagel, G. W.; Schleyer, P. v. R. Efficient diffuse function-augmented basis sets for anion calculations. III. The 3-21+G basis set for first-row elements, Li−F. J. Comput. Chem. 1983, 4, 294− 301. (c) McLean, A. D.; Chandler, G. S. Contracted Gaussian basis sets for molecular calculations. I. Second row atoms, Z = 11−18. J. Chem. Phys. 1980, 72, 5639−5648. (d) Krishnan, R.; Binkley, J. S.; Seeger, R.; Pople, J. A. Self-consistent molecular orbital methods. XX. A basis set for correlated wave functions. J. Chem. Phys. 1980, 72, 650− 654. (43) (a) Bochevarov, A. D.; Harder, E.; Hughes, T. F.; Greenwood, J. R.; Braden, D. A.; Philipp, D. M.; Rinaldo, D.; Halls, M. D.; Zhang, J.; Friesner, R. A. Jaguar: A high-performance quantum chemistry software program with strengths in life and materials sciences. Int. J. Quantum Chem. 2013, 113, 2110−2142. (b) Jaguar, versions 7.0−9.3; Schrödinger, LLC: New York, 2007−2016. 12820 DOI: 10.1021/acs.inorgchem.7b01562 Inorg. Chem. 2017, 56, 12809−12820

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Running head: SYNTHESIS AND CHARACTERIZATION OF COPPER COMPLEXES

Synthesis and Characterization of Copper Complexes
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SYNTHESIS AND CHARACTERIZATION OF COPPER COMPLEXES

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Synthesis and Characterization of Copper Complexes
Abstract
The present paper summarizes the key results obtained by Gibbons et al. (2017) regarding
the synthesis and the characterization of both the structural and optical properties of copper
coordination compounds. The selection of this article founds on the idea of how it binds the
different topics dealt throughout the course, using several of the techniques commonly used in
inorganic, physical, and analytical chemistry laboratories. As discussed throughout the paper, the
appropriate selection of the different ligands forming part of the coordination complex and the
optimization of the experimental conditions affecting the synthesis of such complexes will play a
crucial role on the structural and optical properties of the final compound. I am confident in that
the selected article, through the use of com...

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