Cationic, arylbismuth(III) complexes of the form [BiR2L2]+ and [BiRL4]2+ where L is a neutral two-electron donor ligand
Abstract
Synthetic and structural studies have been made for a range of cationic, ten-electron, four-co-ordinate, diarylbis(ligand)bismuth(III) complexes. Reactions between BiPh2Br, AgBF4 and 2 equivalents of a two-electron donor ligand L afforded the ionic complexes [BiPh2L2][BF4][L = OPPh3 or pyridine (py)]. The first was characterised by X-ray crystallography and comprises [BiPh2(OPPh3)2]+ cations, tetrafluoroborate anions and CH2Cl2 molecules of crystallisation. The bismuth centre is four-co-ordinate with a disphenoidal geometry in which the aryl groups are in equatorial positions with the ligands in axial sites. A long interaction is present between the bismuth centre and one of the fluorines of the BF4 group. A series of similar reactions were also carried out between BiR2Br (R = aryl), TlPF6 and 2 equivalents of L affording the ionic complexes [BiR2L2][PF6][R = Ph, L = OP(NMe2)3 or py; R = 4-MeC6H4, L = OP(NMe2)3; R = 2,4,6-Me3C6H2, L = OP(NMe2)3 or OPPh3]. Two of the complexes have also been characterised by X-ray crystallography, the cations having similar structures to that found in [BiPh2(OPPh3)2][BF4]. The reaction between BiPhBr2, 1 equivalent of TlPF6 and an excess of OP(NMe2)3 afforded the ionic complex [BiPh{OP(NMe2)3}4][PF6]2. The crystal structure of the dication comprises a square-based pyramidal bismuth centre with an apical phenyl group and four basal OP(NMe2)3 ligands. Examples of some dihalogenobismuth cations have also been obtained and their structures are described and compared with those of previously reported examples.