Crystal structure, spectral and electrochemical properties of [TBA]2[Ni(i-MNT)2], [TBA][Ni(i-MNT)2], [TBA]2[Ni(i-MNS)2] and related bis(1,2-dithiolene) metal complexes

The synthesis, crystal structure and physical properties of bis(1,1-dithiolene) or bis (1,1-diselenolene) metal complexes of [TBA]2[Ni(i-MNT)2], [TBA][Ni(i-MNT)2] and [TBA]2[Ni(i-MNS)2] (i-MNT = 2,2-dicyanoethylene-1,1-dithiolate,i-MNS = 2, 2-dicyanoethylene-1, 1-diselenolate) were studied and compared to one another or to the related bis (1,2-dithiolene) metal complexes of 5,6-dihydro-1,4-dithiin-2,3-dithiolate, 1,3-dithiole-2-thione-4,5-dithiolate and 1,3-dithiole-2-one-4,5-dithiolate ligands. The structures of the complexes contain equidistant anionic stacks well separated by the counter cation sheets. The planarity and short C-S or C-Se distances in the structures indicate extensive delocalization of the π-system in the compounds. The relative low conductivities for the complexes are due to the low polarizability, large intra-and inter-stack S ··· S distances, and the relative high on-site electron-electron repulsion energy in the compounds.