Anionic phosphine complexes of antimony(III) and bismuth(III) halogenoanions

Abstract

The reaction between Bil₃, [PPh₄] and an excess of PMe₂Ph afforded the ionic compound [PPh₄][Bil₄(PMe₂Ph)₂] the structure of which has been determined by X-ray crystallography. The anion [Bil₄(PMe₂Ph)₂]^– comprises an octahedral bismuth centre bonded to four iodines and two cis phosphine ligands, although there are some significant distortions from idealised octahedral co-ordination, the origins of which are discussed. From the reaction between SbBr₃ and PEt₃, the ionic complex [PEt₃H][Sb₂Br₇(PEt₃)₂] was isolated, probably as a result of adventitious hydrolysis, and also characterised by X-ray crystallography. A discrete dinuclear anion [Sb₂Br₇(PEt₃)₂]^– is present in this complex with a geometry best described as between face-shared bioctahedral and two square-based pyramids sharing a vertex.