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.