Crystal structure of tetrabutylammonium [bis(1,3-dithiole-2-thione-4,5-dithiolato)bismuthate(1-)], [NBu4][Bi(dmit)2]

The crystal structure of ionic [NBu4][Bi(dmit)2] (5: Q=NBu4), obtained from BiBr3 and [NBu4]2[Zn(dmit)2], has been determined. The bismuth atoms are six coordinate, as a consequence of two inter-anion Bi–S contacts with two neighbouring anions. In addition to the four intra-anion Bi—S bonds to the two thiolato S atoms of the dmit ligands [Bi–S between 2.5872(14) and 2.8082(13) Å: the inter-anion bonds involve thione S atoms [Bi—S(10)i=3.2548(11) and Bi–S(10)ii 3.4628(13) Å]. Excluding consideration of any lone pair effect, the Bi atoms have very distorted octahedral geometries. The anions form centrosymmetric pairs of chains with the shortest Bi–Bi distance of 4.180 Å being between the pairs of chains; overlapping parallel dmit ligands, within the pairs of chains, are separated by a perpendicular distance of 3.477(2) Å, with the dmit centroid–dmit centroid separation of 3.529 Å, ideal for π–π interaction.