Redistribution of Trialkyl Silanes Catalyzed by Iridium Silyl Complexes

[Ir(COE) 2 Cl] 2 reacts with Et 3 SiH at 23 °C to form a binuclear iridium complex (Et 3 Si) 2 (H) 2 Ir(μ-Cl) 2 Ir(H) 2 (SiEt 3 ) 2, 1 . Complex 1 reacts further with Et 3 SiH at 60 °C to form a second binuclear iridium complex, Et 3 Si(H) 2 Ir(μ-SiEt 2 ) 2 Ir(H) 2 SiEt 3, 2, containing bridging Et 2 Si groups. Activation of 2 with H 2 produces trace quantities of a very highly reactive but unobservable species which rapidly and efficiently catalyzes alkyl redistribution reactions of silanes, RR′R″SiH. D 2 and silane exchange experiments establish reactivity features of both 2 and the reactive intermediate. The intermediate cannot be observed, but it is likely a monomeric iridium silyl silylene complex that catalyzes alkyl scrambling via silane exchanges coupled with 1,3-alkyl migrations between silicon centers. DFT calculations support such a mechanism.