Activations of Silanes with [PhB(CH_2PPh_2)_3]Ir(H)(η^3-C_8H_(13)). Formation of Iridium Silylene Complexes via the Extrusion of Silylenes from Secondary Silanes R_2SiH_2

Abstract

The abstraction of methide from (Me_3P)_3Ir(SiHMes_2)(Me)(H) (1) with B(C_6F_5)_3 gave the silylene complex [fac-(Me_3P)_3(H)_2Ir(SiMes_2)][MeB(C_6F_5)_3] (2) via 1,2-hydrogen migration. Secondary silanes (H_2SiR_2) reacted with [PhBP_3]Ir(H)(η^3-C_8H^(13)) (3) (where [PhBP_3] = PhB(CH_2PPh_2)_3^-) to give silylene complexes of the type [PhBP_3](H)_2Ir═SiR_2 (R = 2,4,6-trimethylphenyl (Mes), 4a; R = Ph, 4b; R = Et, 4c; R = Me, 4d), with loss of cyclooctene. Analogously, the germylene complex [PhBP_3](H)2Ir═GeMes_2 was obtained via the reaction of 3 with Mes_2GeH_2. Primary silanes (H_3SiR) reacted with 3 to give [PhBP_3](H)_2Ir═Si(R)(c-C_8H_(15)) (R = Mes, 8a; R = 2,4,6-triisopropylphenyl (Trip), 8b) via an intermediate silylene complex with an Si−H bond, [PhBP_3](H)_2Ir═Si(R)(H). With tertiary silanes (R_3SiH), silyl-capped trihydride complexes of the type [PhBP_3]IrH_3(SiR_3) (R = Et, 7a; R = Me, 7b) and 1,3-cyclooctadiene were produced. The mechanisms of these processes are discussed.

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