Structural studies on phenyl bismuth halides and halogenoanions. Part 2. X-Ray crystal structures of [BiPhCl2(thf)](thf = tetrahydrofuran), [NBun4]2[Bi2Ph2Br6] and [NEt4][BiPh2I2]

Abstract

Structural studies by X-ray crystallography have been carried out on the complexes [BiPhCl₂(thf)]1(thf = tetrahydrofuran), [NBu₄ⁿ]₂[Bi₂Ph₂Br₆]4 and [NEt₄][BiPh₂I₂]6. Complex 1 comprises a chloridebridged polymeric chain with each bismuth centre in a square-based pyramidal co-ordination environment. A phenyl group occupies the apical site whilst the four basal positions are occupied by three chlorine atoms, one terminal and two bridging, and the oxygen of a co-ordinated thf molecule. The chloride bridges are quite asymmetric and a comparison is made with the increasing trend towards symmetric bridges found in the previously characterised bromide and iodide derivatives. The structure of the anionic part of 4 comprises a centrosymmetric [Bi₂Ph₂Br₆]^2– dianion with a planar Bi₂Br₆ unit and trans phenyl groups with each bismuth centre also adopting a square-based pyramidal co-ordination geometry with apical phenyls. Comparisons are made with similar bismuth, antimony and tellurium complexes and the differences discussed. The structure of the anion of 6 can be described as disphenoidal or equatorially vacant, trigonal bipyramidal with axial iodides and equatorial phenyls. This is similar to the previously known bromide complex except that 6 exists in the solid state as a weakly bound centrosymmetric dimer. All of the above structures are compared with those of related compounds and the various trends which are apparent are discussed.