A Route to Base Coordinate Silicon Difluoride and the Silicon Trifluoride Radical

Silicon difluoride (SiF₂) is highly unstable at room temperature and condenses at this temperature rapidly to a polymeric material of unknown structure. Therefore, the isolation of a stable monomeric silicon difluoride species is a challenging task. The cyclic alkyl(amino) carbene (cAAC) coordinated silicon difluoride was isolated as (cAAC)₂SiF₂ (2), synthesized from the reduction of cAAC-SiF₄ (1) by using two equivalents of KC₈ in the presence of one equivalent of cAAC. In the solid state, compound 2 is stable at room temperature for a long time under inert conditions. The reduction of compound 1 in the presence of one equivalent KC₈ resulted in the first stable silicon trifluoride monoradical (cAAC)SiF₃ (3).