Activations of all Bonds to Silicon (Si–H, Si–C) in a Silane with Extrusion of [CoSiCo] Silicide Cores

The [BP3iPr]­Co­(I) synthon
Na­(THF)6{[BP3iPr]­CoI} (1, [BP3iPr] = κ3-PhB­(CH2PiPr2)3–) reacts with
PhSiH3 or SiH4 to form unusual {[BP2iPr]­(SiH2R)­CoH2}Si{H2Co­[BP3iPr]} species (R = Ph, 2a; R = H, 2b; [BP2iPr] = κ2-PhB­(CH2PiPr2)2) that result from activation of all SiH and SiC
bonds in the starting silanes. Solution-spectroscopic data (multinuclear
NMR, IR) for 2a,b, and the solid-state structure
of 2a, indicate substantial CoSiCo multiple
bonding and minimal interaction of the core Si atom with nearby hydride
ligands. In the presence of 4-dimethylaminopyridine (DMAP), 1 reacts with PhSiH3 to give [BP3iPr]­(H)2CoSiHPh­(DMAP) (3). Complexes 2a,b eliminate RSiH3 upon thermolysis in the presence of DMAP to generate {[BP2iPr]­Co­(NC5H3NMe2)}Si{H2Co­[BP3iPr]} (4).