Synthesis and Reactivity of Vaska’s Comple Lab Report

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Synthesis and Reactivity of Vaska’s Comple

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Chem 410 Lab Report Guidelines for Experiment #9 – Synthesis and Reactivity of Vaska’s Complex Experiment #9 can be found on p. 189 of the laboratory manual. Please use the lab report templates available on Blackboard prepare a report based on your assigned section (please see table below). Due Date Experiment 4/12/19 9 Abstract Lab Report Section Assignment Results & Introduction Experimental Discussion 3,8,13 4,9,14 5,10,15 1,6,11 Conclusions 2,7,12 Questions to be Answered: 1) How does the νCO stretching frequency of coordinated CO compare with free CO (2143 cm-1), and how can the difference be explained in terms of bonding (σ and π) with the metal? 2) What is the importance oxidative additions in catalysis? 3) How much does it cost to purchase IrCl3•3H2O and Vaska’s complex? Evaluate the total cost of the materials used in your synthesis. 4) What is the role of aniline in the synthesis of Vaska’s complex? Data to be included in Supporting Information: 1) 2) 3) 4) 5) Cover page with Table of Contents IR spectra of products Sample % yield calculations NMR Spectra of products Carbon copies from lab notebook TITLE (Word Style "BA_Title"). The title should accurately, clearly, and concisely reflect the emphasis and content of the paper. The title must be brief and grammatically correct. Do NOT delete the space above the title. AUTHOR NAMES (Word Style "BB_Author_Name"). Include in the byline all those who have made substantial contributions to the work, even if the paper was actually written by only one person. Use first names, initials, and surnames (e.g., John R. Smith) or first initials, second names, and surnames (e.g., J. Robert Smith). Do not use only initials with surnames (e.g., J. R. Smith) because this causes indexing and retrieval difficulties and interferes with unique identification of an author. Do not include professional or official titles or academic degrees. At least one author must be designated with an asterisk as the author to whom correspondence should be addressed. AUTHOR ADDRESS (Word Style "BC_Author_Address"). The affiliation should be the institution where the work was conducted. If the present address of an author differs from that at which the work was done, indicate with a symbol and give the Present Address under Author Information. If more than one address, use symbols to match author names to address(es). Submitted: [Enter submission date] INTRODUCTION TEXT (Word Style "TA_Main_Text"). For full instructions, please see the journal’s Instructions for Authors. Do not modify the font in this or any other section, as doing so will not give an accurate estimate of the formatting for publication and final length of the paper. FIGURES (Word Style "VA_Figure_Caption"). Each figure must have a caption that includes the figure number and a brief description, preferably one or two sentences. The caption should follow the format "Figure 1. Figure caption." All figures must be mentioned in the text consecutively and numbered with Arabic numerals. The caption should be understandable without reference to the text. Whenever possible, place the key to symbols in the artwork, not in the caption. To insert the figure into the template, be sure it is already sized appropriately and paste before the figure caption. For formatting double-column figures, see the instructions at the end of the template. Do NOT modify the amount of space before and after the caption as this allows for the rules, space above and below the rules, and space above and below the figure to be inserted upon editing. SCHEMES (Word Style "VC_Scheme_Title"). Groups of reactions that show action are called schemes. Schemes may have brief titles describing their contents. The title should follow the format "Scheme 1. Scheme Title". Schemes may also have footnotes (use Word Style "FD_Scheme_Footnote"). To insert the scheme into the template, be sure it is already sized appropriately and paste after the scheme title. For formatting double-column schemes, see the instructions at the end of the template. Do NOT modify the amount of space before and after the title as this allows for the rules, space above and below the rules, and space above and below the scheme to be inserted upon editing. CHARTS (Word Style "VB_Chart_Title"). Groups of structures that do not show action are called charts. Charts may have brief titles describing their contents. The title should follow the format "Chart 1. Chart Title". Charts may also have footnotes (use Word Style "FC_Chart_Footnote"). To insert the chart into the template, be sure it is already sized appropriately and paste after the chart title. For formatting double-column charts, see the instructions at the end of the template. Do NOT modify the amount of space before and after the title as this allows for the rules, space above and below the rules, and space above and below the chart to be inserted upon editing. TABLES. Each table must have a brief (one phrase or sentence) title that describes its contents. The title should follow the format "Table 1. Table Title" (Word Style "VD_Table_Title"). The title should be understandable without reference to the text. Put details in footnotes, not in the title (use Word Style "FE_Table_Footnote"). Do NOT modify the amount of space before and after the title as this allows for the space above and below the table to be inserted upon editing. Use tables (Word Style “TC_Table_Body”) when the data cannot be presented clearly as narrative, when many precise numbers must be presented, or when more meaningful interrelationships can be conveyed by the tabular format. Do not use Word Style “TC_Table_Body” for tables containing artwork. Tables should supplement, not duplicate, text and figures. Tables should be simple and concise. It is preferable to use the Table Tool in your word-processing package, placing one entry per cell, to generate tables. Displayed equations can be inserted where desired making sure they are assigned Word Style "Normal". Displayed equations can only be one column wide. If the artwork needs to be two columns wide, it must be relabeled as a figure, chart, or scheme and mentioned as such in the text. ANSWERS TO QUESTIONS ASSOCIATED CONTENT Supporting Information Word Style "Section_Content"). A listing of the contents of each file supplied as Supporting Information should be included. For instructions on what should be included in the Supporting Information, refer to the Chem 410 syllabus. AUTHOR INFORMATION Corresponding Author (Word Style "Section_Content"). Give contact information for the author(s) to whom correspondence should be addressed. REFERENCES (Word Style "TF_References_Section"). References are placed at the end of the manuscript. Authors are responsible for the accuracy and completeness of all references. Examples of the recommended formats for the various reference types can be found at http://pubs.acs.org/page/4authors/index.html. Detailed information on reference style can be found in The ACS Style Guide, available from Oxford Press. Table of Contents Graphic (TOC) 3 EXPERIMENT 19 d IR Microscale Synthesis of Vaska's Complex 1, 20. IrCI(CO)[P(C6H5)3]2 V. L Hal: BI 1989 tma- G.; **This experiment requires about 6 hours spread over two laboratory periods. The exament will introduce you to the use of microscale techniques, the ang O compounds on a scale of 100 mg or less. One of the advantages of BRZle synthesis is the low cost of working with small amounts of reagents breats. This consideration is particularly important in this experiment, We are that evaporations and filtrations proceed more quickly than with ih uy the expensive metal iridium. Other advantages of microscale tech- 2. with practice, microscale syntheses are easier than gram-scale chemistry so macational scale synthesis, and reaction wastes are minimized. You will find Se ik number of transfers and to use small reaction vessels. wants of the sample adhering to the apparatus. Thus it is important to mim- is the Con bonyl York, US- Many important concepts in organometallic chemistry relevant to reactivity and catalysis are illustrated by the behavior of the complex prepared in this exrimenttrans-chlorocarbonyibis(triphenylphosphine)iridium(I). Or taco)PC Hs)s). This compound is called Vaska's complex in recognition of researcher who first demonstrated its versatile chemical properties, Vaska's complex is a square planar complex of iridium(1) with trans-triphenyl- peine ligands: 1993, from stuna o 2. G: Try of (CoHs)3P > P(CH3)3 El 6 ntary Vaska's complex nicely illustrates the concept that the reactivity of a metal caplex is related to its valence electron count. Complexes with 18 valence elec- New vers are called saturated and generally do not bind other ligands. Compleres fa 16 valence electrons, such as Vaska's complex, are unsaturated and able to A certain two-electron donors, L, to form adducts: hemi ation *2370- I-CH(COJIP(C2Hslala Ircl{co){P{C;Hs)al24 + L 189 spray 18 e complex 16 € complex Part 1V / ORGANOMETALLIC CHEMISTRY EXP 192 Note reacts with the compound. If you examine the spectrum of IrCl(COP(Hsbla a KBr pellet, you should consider the possibility that Brº/Cl- exchange occurs to The most prominent absorption in the IR spectrum of Vaska's complex is the carbonyl (CO) stretching band, which is usually symbolized vco. The vibrational frequency of CO ligands is sensitive to the electronic properties of the metal center quan form IrBr(CO)/P(C6H3);. hana by virtue of the overlap of the CO n' orbital with metal d orbitals: BOIS e e Biser In a plaa mmo anili bubb of N altit yield Iridium(1) - CO Interaction Iridium(III) - CO Interaction of m yello each prod Oxy In a of 10 Generally, the transfer of electron density from the metal to the CO T* orbital is more efficient when the metal is in a low oxidation state. This transfer of elec- tron density, called a back-bonding, strengthens the M-C bond and weakens the C-0 bond because the gº orbital is antibonding with respect to C and O. This logic suggests that the ico frequency in CO complexes will decrease as more back-bonding occurs. These concepts are important for analyzing the bonding between metals and CO; the bonding of many other ligands, including alkenes, acetylenes, N3, and isocyanides, can be analyzed in a similar way. The characterization of CO complexes by IR spectroscopy is very convenient because the CO stretching bands occur in a region where fèw organic molecules absorb. Furthermore, co stretching bands are usually rather intense; con- sequently, it is possible to record spectra from extremely dilute solutions. The roo bands of metal carbonyls are even more intense than the ico bands seen for organic carbonyls such as ketones and esters, The voo band for the iridium(I) compound IrCl(CO)P(C6Hs);}; is found near 1960 cm -, whereas in the iridium(III) compound IrCl3(CO)[PC Hshh it appears at 2120 cm). This frequency shift indicates that the C-o bond is stronger (and the Ir-C bond weaker) in the latter complex. For the O, complex IrCl(CO)[P(C6Hshl:(03) the CO stretching band occurs at 2010 cm suggests that the O, ligand withdraws electron density less effectively than two chloride ligands . In the present experiment, the relative amounts of Ircico)P(C6H,)sh and Ircico[PC Hs);};(0) can be estimated from the relative intensities of the yco bands at 1960 and 2010 cm CUSSI then the resid mits sirea resid IR S This 1. P which 2. A Thuis Experiment 19 Microscale Synthesis of Vaska's Complex IrCi(CO) P(Cehshalz 193 EXPERIMENTAL PROCEDURE Vole: Indium salts can cost up to US$100 per gram, so it is essential to use small quantities in this experiment. When small amounts of compounds are being handled, it is important to minimize mechanical losses by using small reaction vessels and by reducing the number of times the sample is transferred, lo en cale trans-IrCi(CO)[P(CHz)sk In a 50-mL round-bottom flask mounted in a rheostat-controlled heating mantle, place a Tefion-coated stir bar, 0.105 g (0.3 mmol) of LC13-3 H20,* 0,393 g (I.S mmol) of triphenylphosphine, 10 mL of dimethylformamide, and 0.120 mL of aniline. Fit the flask with a reflux condenser topped with a N, inlet connected to a bubbler. Briefly flush she air from the system with a Nz stream. Decrease the fios Teing kept -1000 around / of Nz gas and heat the mixture to vigorous reflux for 2 h (or longer at higher altitudes). Heating can be continued for up to 24 h without adversely affecting the yield . Allow the yellow solution to cool to 50 °C (or below) and then add 30 ml of methanol. Cool the mixture in an ice bath for 10 min and then collect the yellow microcrystals by filtration in air. Wash the crystals with a few milliliters each of methanol and diethyl ether, and then dry the solid in a vacuum. Solid samples of Vaska's complex are air stable. Record the yield, and save some of the product for an IR spectrum. NMR sal in Chlorate ge Oxygeaation of IrCKCO)[P(CsHsbh2 In a 100-ml Schlenk flask containing a magnetic stirring bar, prepare a solution of 40 mg of Vaska's complex in 20 mL of toluene (see Experiment 17 for a dis- cussion of Schlenkware). While stirring the solution, flush the fask with O, gas, then close off the stopcock and stopper the fiask. Vigorously stir the solution in the O2 atmosphere for 90 min. Evaporate the solution to obtain a yellow-orange residue. Record the IR spectrum of some of the solid as a Nujol mull. Time per- mitting, redissolve the remainder in toluene and purge the solution again with a Stream of N, gas. Once the solvent has evaporated, remove some of the solid residue and examine ils IR spectrum. pt IR Spectra as Nujol Mulls This section describes in detail a method for preparing mulls of compounds. 1. Put about 5 mg of the complex in a polished agate mortar and grind the sample with an agate pestle until the substance forms a glossy layer in the mortar (between 1 and 5 min of grinding). The extent of grinding will make the difference between a good and a bad spectrum. 2. Add a small drop of the Nujol (or other mulling agent) to the lip of the mor- lar, With the pestle, transfer a small amount of the mulling agent to the powder, Grind this mixture, adding more mulling agent il necessary. all of the sample has been converted into a paste. Roure la cucle sunt 431 Un me BUDO sites she શુ છું તો તારા પતિ માતા રામાપીર દા ા છે તો તમારા
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Synthesis of Vaska’s complex by microscale synthesis
John R. Smith
AUTHOR ADDRESS (Word Style "BC_Author_Address"). The affiliation should be the institution where the work was
conducted. If the present address of an author differs from that at which the work was done, indicate with a symbol and give
the Present Address under Author Information. If more than one address, use symbols to match author names to address(es).

Submitted: [Enter submission date]

INTRODUCTION
The synthesis of a compound by microscale techniques has advantages over conventional synthesis as lower amounts of solvents and solutes (less than 100 mg) are used. In addition, a microscale synthesis is usually used when a limited amount of reagent is available or when the reagent is valuable. In this experiment very expensive metal was used, iridium (Ir). The microscale
synthesis is environmentally friendly as low amount of waste is
generated after finishing the synthesis.
Relating the technical characteristics of the microscale synthesis, it is crucial to use small reaction vessels and to minimize
sample handling.
Throughout the understanding of the behavior of transchlorcarbonyl bis (triphenylphosphine) iridium (I) or
IrCl(Co)[P(C6H5)3]2 also known as Vaska’s Complex, many important concepts in organometalic chemistry can be explained. As
the iridium has 16 electrons (unsaturated) it can be easily forms
the complexes.
The complex can react with the wide number of molecules (H2,
HCl, CH3I, etc) during which iridium could be inserted into the σ
bond of a certain molecule. This chemical reaction is called oxidative addition.
The importance of Vaska’s complex lies in fact that this complex could reversibly to bind oxygen. By mentioned reaction it
can be performed the simulation of biological carriers of
O2.During this reaction Ir center becomes IIII.
By using IR spectroscopy, the characterization of bounds in Vaska’s complex is usually carried out. The most frequently used IR
techniques is by measuring of IR spectrum of compound dissolved in appropriate solvents. Other mechanisms involve analysis of a compound as a mull, or as a compressed solid pallet. The
application of the mull is a challenging task and this technique is
rarely used in the Vaska’s complex characterization. By the application of pellet techniques, the mixture of IR transparent (KBr)
substances and the Vaska’s complex is combined in order to prepare fine powder. During the KBr application possible interference could be expected.
In the Vaska’s complex, one of the most important groups for
absorption of IR spectrum is carbonyl (CO) group. Additionally,
CO group in the Vaska’s complex absorb IR spectrum in a region
where only few organic compounds absorb. The interaction of the
CO π orbital with the iridium d orbital contributes to this fact.
During this interaction the electron density is transferred to the
CO π* orbital. As a consequence, the carbonyl stretching band in
CO complexes decrease.

ANSWERS TO QUESTIONS
Answer 1) In the coordinated CO, the absorption of
the IR spectrum occurred as a consequence of the
overlapping of the π orbital and d orbital of the metal. In the...


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