Reactivity of a Phosphinoamidinate-Stabilized Disilylene toward H-X Bonds.

An efficient method for the preparation of a phosphinoamidinate-supported disilylene was developed, and its reactivity toward H-E bonds (E = elements from Groups 13-15) was studied. With HBpin, transfer of the ligand from silicon to boron was observed to afford (NP)Bpin. Reaction with a silane (H3SiPh) took place only at elevated temperatures, at which point oxidative addition of the N-P bond of the NP-ligand to one of the silicon atoms of the disilylene occurred prior to Si-H addition involving the remaining silylene center. In contrast, reaction of the disilylene with phosphine, HPPh2 furnished the phosphidosilylene (NP)SiPPh2 (16) together with a highly transient species that, on the basis of a trapping experiment with H3SiPh, is proposed to be the hydridosilylene (NP)SiH, 17. Interestingly, 16 reacts with HPPh2 to give the diphosphine (PPh2)2, most likely via a direct σ-bond metathesis process. The aforementioned products have been characterized by multinuclear NMR and single-crystal X-ray diffraction studies.