Alkylation of iridium via tandem carbon-hydrogen bond activation/decarbonylation of aldehydes. Access to complexes with tertiary and highly hindered metal-carbon bonds

Reactions between Cp*(PMe3)Ir(Me)OTf (1) and aldehydes (RCHO) proceed with high selectivity to give the hydrocarbyl carbonyl salts [Cp*(PMe3)Ir(R)(CO)][OTf] (R = Me (2), Et (3), n-Pr (4), c-Pr (5), Ph (6), 1-ethylpropyl(7), p-tolyl(8), mesityl(9), 2-(Z)-1-phenylpropenyl (10), vinyl(13), t-Bu (14), 1-adamantyl(17)). This tandem C-H bond activation/decarbonylation reaction provides access to the first isolated tertiary alkyl complexes of iridium. X-ray diffraction studies were performed on mesityl complex 9, tert-butyl derivative 15, and 1-adamantyl compound 18. Decarbonylation of cyclopropyl complex 5 results in irreversible opening of the cyclopropyl ring. This reaction has provided useful information concerning the mechanism of C-H activation of cyclopropane by 1. Hydride reduction of the p-tolyl carbonyl salt 8 has provided an example of a rare transition-metal formyl complex, Cp*-(PMe3)Ir(p-tolyl)(CHO) (28).