Electrocrystallization, X-ray structure and electronic properties of the dmit-based salt [MePh(3)P][Ni(dmit)(2)](3)

Electrooxidation of [Ni(dmit)(2)](-)(dmit = C3S52- = 4,5-dithiolate-2-thione-1,3-dithiole) in 3 : 1 acetonitrile-acetone at a Pt wire anode in the presence of methyltriphenylphosphonium bromide electrolyte yields the radical anion salt complex [MePh(3)P][Ni(dmit)(2)](3). Black shiny platelet crystals were harvested. They belong to the monoclinic space group P2(1)/c, M = 1631.41, alpha = 21.0872(1), b = 17.3930(2), c = 15.7203(2)Angstrom,beta = 107.072(1)degrees, V = 5543.4(1) Angstrom(3) and Z = 4. The crystal packing structure consists of columns of Ni(dmit)(2) units of width one unit separated by columns of MePh(3)P(+) counter-ions. The Ni(dmit)(2) columns are composed of dimers of Ni(dmit)(2) units with non-bonding interactions with six other pairs of Ni(dmit), units. The arrangement of the dimers with respect to each other in the columns has been seen in other phosphonium-based Ni(dmit), complexes and is similar to the packing of kappa-BEDT-TTF radical cation salts which have shown superconductivity. Single-crystal temperature-dependent conductivity measurements have shown that this material is semiconducting with a room-temperature conductivity of 0.1 S cm(-1) and a thermal activation energy of 0.22 eV.