Tris allyl iridium and -Rhodium

Submitted by KEVIN D. JOHN, JUDITH L. EGLIN, KENNETH V. SALAZAR, R. THOMAS BAKER, and ALFRED P. SATTELBERGER  

Checked by DANIEL SERRA and LISA MCELWEE WHITE  

The investigation of tris(allyl)iridium for the preparation of single-site catalysts with better thermal and reductive stability resulted in the development of improved synthetic routes to both the iridium and rhodium analogs. The syntheses of M(allyl)3, modified syntheses of MCl3(THT)3 precursors (THT = tetrahydrothio- 

Inside a glove box, M-butyULthium (7.1 mL of a 2.5 M solution in hexanes, 17.7 mmol) is redueed to a thiek oil under vacuum at room temperature. The pale yellow n-butyUithium oil is then dissolved in diethyl ether (5 mL). This solution is added dropwise over 5 min to a stirred solution of tetra(aUyl)tin (2.5 g, 8.83 mmol) in diethyl ether (40 mL) in a lOOmL Erlenmeyer hask. The solution is stirred for 15 min before most of the solvent is removed under vacuum. To the resultant paste, hexane (25 mL) is added and the resultant suspension is stirred vigorously for 30 min. If the trituration fails to provide a white sohd, vigorous scraping of the flask walls with a spatula usually affords the desired powder. Alternatively, the hexane can be deeanted and fresh hexane added and the agitation repeated. The product is filtered and rinsed with hexane (2 X lOmL) to give a white powder. Yield 0.74 g (87%). 

AllyUithium is a pyrophoric white solid. Solid samples stored under an inert atmosphere at room temperature beeome yellow over time (days) and lose then-effectiveness. Samples should be stored at —20°C or prepared immediately before use. Fresh samples ean be dissolved readily in ether solvents to give pale yellow solutions. AUylhthium is insoluble in aliphatic hydrocarbons, slightly soluble in aromatic solvents, and reaets with methylene ehloride, chloroform, and acetonitrile. The produet ean be dissolved in pyridine to provide orange solutions for NMR analyses. H NMR (NC5D5, 25°C) 8 6.25 (s, IH, CH2-C//=CH2), 5.19-5.11 (m,2H,CH2 CH=C7/2), 2.56 (s, 2H, C7/2-CH=CH2). C H NMR (NC5D5, 25°C) 8 138.99 (1C, CH2-CH=CH2), 114.44 (1C, CH2-CH=CH2), 50.74 (1C, CH2 CH=CH2). Note that the ehemical shifts in pyridine solvent indicate sigma eoordination of the aUyl anion to the lithium cation, unlike the )t-coordination observed in THF. ° 

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