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

Highly conducting, mixed-valence, multi-component nickel bis-(diselenolene) salts were obtained by electrocrystallization of the monoanionic species [Ni(Me-thiazds)(2)](-1 )(Me-thiazds: N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate), with 1:2 and 1:3 stoichiometries depending of the counter ion used (Et4N+ and nBu(4)N(+) vs Ph4P+, respectively). This behavior strongly differs from that of the corresponding monoanionic dithiolene 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 [Ph4P][Ni(Me-thiazds)(2)](3 )and the quasi metallic character of [Et4N][Ni(Me-thiazds)(2)](2) and [NBu4](x)[Ni(Me-thiazds)(2)](2) salts (0 < x < 1).

Automated summary

Highly conducting, mixed-valence, multi-component nickel bis-(diselenolene) salts were obtained by electrocrystallization. Depending on the counter ion used, the salts showed different stoichiometries of 1:2 and 1:3. This is a rare example of mixed-valence conducting salts of nickel diselenolene complexes, which usually form single component neutral species. The transport measurements under high pressure and band structure calculations confirmed the semiconducting and quasi metallic characters of the salts.