Iridium silylenoids

Tilley and coworkers reported a more direct procedure for the synthesis of late transition metal silylenoid complexes by reaction with silanes [equation (7.1)].36,37 Exposing iridium complex 14 to dimesitylsilane afforded iridium silylenoid 15.36 In addition to dimesitylsilane, other silanes could be used, including diphenyl-, diethyl-, or dimethylsilane. Primary silanes such as mesitylsilane and 2,4,6-triisopropylphe-nylsilane were also tolerated as substrates.37... 

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. 

Iridium silylenoids were also reported to catalyze the hydrosilation of ketones [equation (7.7)].57 The room temperature reduction of acetophenone was achieved using only 5 mol% of silylenoid 34 to afford alkoxysilane 35 and ethyl benzene. In addition to acetophenone, acetone was also reported as a competent substrate for hydrosilation. 

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See also in sourсe #XX -- [ ]

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