Synthesis of [bis(1,3-dithiole-2-thione-4,5-dithiolato)indium(III)]− salts, [Q][In(dmit)2]: crystal structure of [tetrabutylammonium][bis(1,3-dithiole-2-thione-4,5-dithiolato)indium(III)]

Ionic complexes, [Q][InIII(dmit)2] (7), have been obtained from reactions of InCl3, Na2(dmit) and [Q]Br [Q=NEt4 and NBu4: H2(dmit)=4,5-dimercapto-1,3-dithiole-2-thione]. As established by X-ray crystallography, using synchrotron radiation at 120 K, (7: Q=NBu4) is an ionic compound, with the cations well separated from the anions. The anions are in the form of chains of edge sharing octahedra in which distinct six coordinate In atoms are linked by bridging thiolato-S leading to the formation of In2S2 rings. For each dmit ligand, one thiolato S atom acts as a monodentate centre and the other as a μ2-bridge. The In–S bond lengths fall into three groupings: 2.5301(17)–2.5400(17) [monodentate S], 2.5905(17)–2.6171(17) and 2.7236(17)–2.7589(17) Å [the latter two, bridging S].