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.