Activation of carbon-hydrogen bonds in saturated hydrocarbons on photolysis of (.eta.5-C5Me5)(PMe3)IrH2. Relative rates of reaction of the intermediate with different types of carbon-hydrogen bonds and functionalization of the metal-bound alkyl groups

TLDR: In this article, a 500 W Oriel focused-beam mercury lamp was used to generate hydrido alkyl iridium complexes (HRIr) in saturated hydrocarbons.

Abstract: Irradiation of (eta/sup 5/-pentamethylcyclopenta-dienyl)(trimethyl phosphine) dehydroiridium (eta/sup 5/-C/sub 5/Me/sub 5/)(PMe/sub 3/)IrH/sub 2/ in saturated hydrocarbons using a 500 W Oriel focused-beam mercury lamp leads to extrusion of hydrogen and production of the hydrido alkyl iridium complexes (----HRIr). Competition experiments were used to measure relative rates at which the intermediate formed on hydrogen loss reacts with different types of C-H bonds. Relative to cyclohexane (1), these rates are: benzene (4), cyclopropane (2.65), cyclopentane (1.6), neopentane (1.14), cyclodecane (.23), and cyclooctane (.09). Reductive elimination of hydrocarbon occurs at elevated temperature, regenerating the intermediate, which may then react with another hydrocarbon acting as solvent. The factors which presumed to influence the rates of reaction of transition-metal complexes with saturated C-H bonds are discussed.