Iridium complexes redistribution reactions

In addition to ruthenium, Tilley and coworkers also reported that cationic iridium silylenoid complexes were efficient olefin hydrosilation catalysts [reaction (7.6)].56 This silylene complex catalyzes the hydrosilation of unhindered mono- or disubsti-tuted olefins with primary silanes to produce secondary silanes with anti Markovni-kov selectivity. Iridium catalyst 32 exhibited reactivity patterns similar to those of ruthenium 30 only primary silanes were allowed as substrates. In contrast to 30, cationic iridium 32 catalyzed the redistribution of silanes. Exposing phenylsilane to 5 mol% of 32 in the absence of olefin produced diphenylsilane, phenylsilane, and silane. 

Molecular oxygen adducts of transition metal complexes arc of interest and importance to catalytic processes and commercial oxidation processes, as well as being intermediates in oxidation reactions. Vaska " has reviewed the nature of dioxygen bound to transition metal complexes. All known iridium dioxygen complexes possess the peroxo structure (140). Experimental data reveal that the formation of covalent Ir—(O2) bonds on dioxygen addition to IrL, is accompanied by extensive redistribution of electrons, and the electron transfer is from the iridium to dioxygen. SCF-X -SW calculations on [Ir(02)(Ph3)4] and [Ir(Ph3)4] " indicate peroxo -metal bonding. ... 

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