Cooperative Si–H Addition to Side-On Ni(0)-Imine Complexes Forms Reactive Hydrosilazane Complexes

Activation
of a Si–H bond is commonly a critical step in
catalytic hydrosilylation reactions. Herein, we investigate the cooperative
reactivity of Ni(0) centers bearing a side-bound imine ligand toward silanes. Such complexes
activate a Si–H bond of diphenylsilane, resulting in formal
hydrosilylation of the imine backbone, which acts as a hydride acceptor.
The resulting hydrosilazane motif engages either in coordination to
nickel via the Si–H bond, forming an 18-electron η2-Si–H complex, or oxidative addition to Ni to form
16-electron Ni­(II) silyl/hydride complexes. DFT calculations suggest
a cooperative activation of the silane via ligand-to-ligand hydride
transfer. In addition, the silicon fragment readily exchanges with
external hydrosilanes, showing that the Si–N bond can be reversibly
cleaved under mild conditions.