Molecular and Crystal Structure, and EPR Studies of Tetraphenylarsonium [Bis-(l,3-dithia-2-one-4,5-dithiolato)-nickelate], (AsPh4)[Ni(dmid)2]

Crystal Structure, EPR Studies, Tetraphenylarsonium [Bis-( 1,3-dithia-2-one-4,5-dithiolato)-nickelate] The crystal structure of (AsPh4)[Ni(dmid)2] (dmid ~ = 1,3-dithia-2-one-4,5-dithiolato) has been determined by X-ray diffraction studies: crystals are monoclinic, space group P2,//i, a = 14.724(2), b = 14.305(5), c = 15.570(3) k , ß = 92.20(1)°, V = 3277 Ä, ov = 1.63 gem 3 for Z = 4, final conventional agreement indices R = 0.038 and Rw = 0.049 for 2115 unique, observed reflections and 211 variable parameters. The asymmetric unit contains one (AsPh4) cation and one [Ni(dmid)2] anion, both in general positions. The anions are isolated from each other by the bulky cations. The [Ni(dmid)2]~ ion deviates strongly from planarity: the dihedral angle between the two Ni(dmid) moieties is 10.7°; one of the dmid ligand is almost planar, while the second one is severely puckered. Polycristalline powder and single crystal EPR spectra have been recorded at room temperature. Only one signal was observed in all crystal orientations. The angular dependences of the linewidth and of the g values have been determined, as well as the principal g values and directions. These results have been compared to those previously obtained for the analogue (Aj-Bu4N)[Ni(dmit)2] (drnit" = 1,3-dithia-2-thione-4,5-dithiolato), and discussed in terms of the localization of the unpaired electron on the ligands. leading to a formal (III) and actual (II) nickel oxidation state.