Base-Free Iron Hydrosilylene Complexes via an α-Hydride Migration that Induces Spin Pairing.

Two new base-free hydrosilylene complexes of iron were synthesized using the novel starting material Cp*( iPr2MeP)FeMes. These Cp*( iPr2MeP)Fe(H)SiHR (R = DMP, Trip) complexes are in equilibrium with the corresponding iron silyl complexes, Cp*( iPr2MeP)FeSiH2R, which can be trapped and characterized for R = Trip. Unlike the Ru analogues, the Fe silylene complex with R = DMP is observed to undergo an intramolecular C-H activation involving formal addition of a benzylic C-H bond across the Fe-Si bond. This increased activity for bond activations is also observed for reactions with hydrogen, where Fe reacts faster than a Ru analog to form the hydrogenation product, Cp*( iPr2MeP)H2FeSiH2DMP.