Preparation and characterization of metal complexes with an extended TTF dithiolato ligand, bis(propylenedithiotetrathiafulvalenedithiolato)-nickel and -cuprate

Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiol [ptdt(2-) =(S8C9H6)(2-)], have been synthesized. Characterization of monoanionic tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt)(2)(-) and the dianionic tetraphenylphosphonium salt of Cu(ptdt)(2)(2-) have been performed, using cyclic voltammetry, electrical resistivity measurements, magnetic susceptibility measurements and X-ray crystal structure determination. The geometries around the Ni atoms are almost square planar. In both Ni complexes, one of the extended ligands of Ni(ptdt)(2)(-) is overlapping with that of the adjacent anion separated by about half of the unit of the molecule, forming a one-dimensional chain. The adjacent chains are connected by transverse short S ... S contacts. Cu(ptdt)(2)(2-) has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato ligand is 54.2 degrees. The crystal structures of Ni(ptdt)(2)(-) and Cu(ptdt)(2)(2-) complexes show the possibility of novel 2D or 3D intermolecular contacts through ptdt ligands. The complex [Me4N][Ni(ptdt)(2)].Me2CO is a semiconductor with a room temperature conductivity of 1.4 x 10(-3) S cm(-1) and activation energy of 9.9 x 10(-2) eV.