Mixed-Valence Conductors from Ni Bis(diselenolene) Complexes with a Thiazoline Backbone.

Highly conducting, mixed-valence, multi-component nickel bis() salts were obtained by electrocrystallization of the monoanionic species [Ni(Me-thiazds)] (Me-thiazds: -methyl-1,3-thiazoline-2-thione-4,5-diselenolate), with 1:2 and 1:3 stoichiometries depending of the counter ion used (EtN and BuN PhP, respectively). This behavior strongly differs from that of the corresponding monoanionic complexes whose oxidation afforded the single component neutral species. This provides additional rare examples of mixed-valence conducting salts of nickel diselenolene complexes, only known in two examples with the dsit (1,3-dithiole-2-thione-4,5-diselenolate) and dsise (1,3-dithiole-2-selone-4,5-diselenolate) ligands. The mixed-valence salts form highly dimerized or trimerized bi- and trimetallic units, rarely seen with such nickel complexes. Transport measurements under a high pressure (up to 10 GPa) and band structure calculations confirm the semiconducting character of [PhP][Ni(Me-thiazds)] and the metallic character of [EtN][Ni(Me-thiazds)] and [NBu][Ni(Me-thiazds)] salts (0 < < 1).