Synthesis and properties of bis(1,3-dithiole-2-thione-4,5-dithiolato)bismuthate(1-) salts, [Q][Bi(dmit)2].: Crystal structure of [AsPh4][Bi(dmit)2]•1/2DMSO:: comparison of the solid state structures of [Q][Bi(dmit)2] and [Q][Sb(dmit)2]

Ionic complexes, [Q][Bi(dmit)(2)] (5:Q=NEt4, NBu4, 1,4-Me-2-pyridinium and AsPh4), have been obtained from BiBr3 and [Q](2)[Zn(dmit)(2)] [H-2-dmit=4,5-dimercapto-1,3-dithiole-2-thione]. As established by the crystal structure determination of [(5:Q=AsPh4).1/2DMSO], the cations have near tetrahedral geometries and are well separated from the anions. The anions, containing chelating dmit ligands, are linked into chains via Bi-thiolato-S inter-anion bonds: Bi2S2 rings are formed within the chains, with Bi . . . Bi distances alternating between 3.7760(3) and 3.9092(3) Angstrom. The bismuth atoms are six-coordinate, arising from two inter-anion Bi-S [Bi-S = 3.0391(13) and 3.1643(14) Angstrom] and four intra-anion Bi-S bonds [between 2.6680(13) and 2.8370(13) Angstrom], with stereochemistries, including the equatorial-sited stereochemically active lone pair, of distorted pentagonal bipyramids. There are no S . . .S contacts between the anions less than the sum of the van der Waals radii. Comparisons are made between the structure of [(5:Q=AsPh4).1/2DMSO] and those reported previously for (5:Q=NEt4), [(5:Q=NEt4).1/2Et(2)O] and [(5:Q=NBu4) as well as those for [Q][Sb(dmit)(2)] (4), (C) 2001 Elsevier Science B.V. All rights reserved.