Phosphorus derivatives of mesoionic carbenes: synthesis and characterization of triazaphosphole-5-ylidene → BF3 adducts

Abstract

Trimethylsilyl-substituted triazaphospholes were synthesized by a [3+2] cycloaddition reaction between organic azides and (CH₃)₃Si–CP. In an attempt to isolate their N-alkylated products, the formation of BF₃ adducts of unprecedented triazaphosphol-5-ylidenes was found. The nature of the carbon_carbene–boron bond was investigated within the DFT framework, revealing a strong donation of electrons from the carbene carbon atom to the boron atom combined with weak back-bonding.