Bis(tetra-n-butylammonium) (a redetermination at 150 K) and bis(tetraphenylarsonium) bis(1,3-dithiole-2-thione-4,5-dithiolato)zinc(II) (at 300 K)

The title compounds are salts of the general form (Q(+))(2)[Zn(dmit)(2)](2-), where dmit corresponds to the ligand (C3S5)(-) present in both and Q(+) to the counter-cations ((Bu4N)-Bu-n)(+) [or C16H36N+] and (Ph4As)(+) [or C24H20As+], respectively. In the first case, Zn is in the 4e special positions of space group C2/c and hence the [Zn(dmit)(2)](2-) dianion possesses twofold axial crystallographic symmetry. Including these, there are now 11 known examples of [Zn(dmit)(2)](2-) or its analogues, with O replacing the exocyclic thione S, and [Zn(dmio)(2)](2-) dianions in nine structures with various Q. Comparison of these reveals a remarkable variation in details of the conformation which the dianion may adopt in terms of Zn coordination, equivalence of the Zn-S bond lengths, displacement of Zn from the plane of the ligand and overall dianion shape.