Reductive Catenation of Phosphine Antimony Complexes.

Reactions of triarylphosphines with fluoroantimony(III) triflates give phosphine antimony(III) complexes, which undergo spontaneous reductive elimination of fluorophosphonium cations. The resulting phosphine antimony(I) complexes catenate to give the first examples of cationic antimony bicyclic compounds, [(R3P)4Sb6](4+), featuring a bicyclo[3.1.0]hexastibine framework stabilized by four phosphine ligands. The unprecedented 14-electron redox process illustrates the generality of the reductive catenation method.