An H‐Substituted Rhodium Silylene

Divergent reactivity of organometallic rhodium(I) complexes, which led to the isolation of neutral rhodium silylenes, is described. Addition of PhRSiH2 (R=H, Ph) to the rhodium cyclooctene complex (iPrNNN)Rh(COE) (1‐COE; iPrNNN=2,5‐[iPr2P=N(4‐iPrC6H4)]2N(C6H2)−, COE=cyclooctene) resulted in the oxidative addition of an Si−H bond, providing rhodium(III) silyl hydride complexes (iPrNNN)Rh(H)SiHRPh (R=H, 2‐SiH2Ph; Ph, 2‐SiHPh2). When the carbonyl complex (iPrNNN)Rh(CO) (1‐CO) was treated with hydrosilanes, base‐stabilized rhodium(I) silylenes κ2‐N,N‐(iPrNNN)(CO)Rh=SiRPh (R=H, 3‐SiHPh; Ph, 3‐SiPh2) were isolated and characterized using multinuclear NMR spectroscopy and X‐ray crystallography. Both silylene species feature short Rh−Si bonds [2.262(1) Å, 3‐SiHPh; 2.2702(7) Å, 3‐SiPh2] that agree well with the DFT‐computed structures. The overall reaction led to a change in the iPrNNN ligand bonding mode (κ3→κ2) and loss of H2 from PhSiRH2, as corroborated by deuterium labelling experiments. Dehydrogenation of PhSiH3 and Ph2SiH2 led to isolation of neutral silylene complexes, including a rare hydrogen‐substituted silylene. These species represent the first examples of structurally characterized rhodium silylenes, which have long been sought because of their importance as key intermediates in hydrosilation catalysis.