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

Abstract

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.