Synthesis and Reactivity of Bidentate N-Heterocyclic Carbene-Phosphinidene Supported Si(IV) Dicationic Complexes

Herein, we report the synthesis and isolation of Si(IV) dications stabilized by a bidentate N-heterocyclic carbene-phosphinidene (NHCP). Treatment of the bis(NHCP) with Si(IV) bis(triflate) R₂Si(OTf)₂ (with R=H, Ph) resulted in the instant formation of Si(IV) dicationic complexes [2 a] and [2 b] featuring a tetracoordinated silicon centre. The dications show expected high Lewis acidity. The bis(NHCP)-stabilized parent silyl dication 2a (SiH₂²⁺) presents the first isolable example of a parent SiH₂ dication. In addition, dication [2 a] is able to react with diphenylketene by insertion into the Si−P bond.