Treatment of Silylene-Phosphinidene with Chalcogens Resulted Exclusively in the Formation of Silicon-Bonded Chalcogens.

Chalcogen-bonded silicon phosphinidenes LSi(E)-P- cAAC (E=S (1); Se (2); Te (3); L=PhC(NtBu) ; cAAC=C(CH )(CMe ) N-2,6-iPr C H )) were synthesized from the reactions of silylene-phosphinidene LSi-P- cAAC (A) with elemental chalcogens. All the compounds reported herein have been characterized by multinuclear NMR, elemental analyses, LIFDI-MS, and single-crystal X-ray diffraction techniques. Furthermore, the regeneration of silylene-phosphinidene (A) was achieved from the reactions of 2-3 with L'Al (L'=HC{(CMe)(2,6-iPr C H N)} ). Theoretical studies on chalcogen-bonded silicon phosphinidenes indicate that the Si-E (E=S, Se, Te) bond can be best represented as charge-separated electron-sharing σ-bonding interaction between [LSi-P- cAAC] and E . The partial double-bond character of Si-E is attributed to significant hyperconjugative donation from the lone pair on E to the Si-N and Si-P σ*-molecular orbitals.