An N-phosphinoamidinato borasilenide: a vinyl-analogous anion containing a base-stabilised B = Si double bond

Borasilenes, which feature a heterodinuclear Si B double bond, show interesting reactivities, due to two proximal reactive sites—boron and silicon—each with distinct electronic properties. However, borasilenes remain relatively rare due to the challenge of stabilising them. To achieve a stable borasilene, both the boron and silicon centers must be supported by sterically hindered ligands, which can, however, interfere with their potential applications. In this work, we report the synthesis of an N-phosphinoamidinato potassium borasilenide (compound 3), which is a vinyl-analogous anion containing a base-stabilised B=Si⁻ double bond. This B=Si⁻ double bond is functional and exhibits new patterns of reactivity towards CuCl(PMe₃), [IrCl(cod)]₂, Me₃SiOTf, and MeOTf, leading to the formation of a transition metal π-complex, boron-silicon-containing metallacycle, neutral borasilene and borylsilane, respectively.