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

Abstract

Novel monoanionic nickel and dianionic copper complexes with the extended TTF dithiolato ligand, propylenedithiotetrathiafulvalenedithiolate [ptdt2–=(S8C9H6)2– ], have been synthesized. Characterization of monoanionic tetraphenylphosphonium and tetramethylammonium salts of Ni(ptdt)2– and the dianionic tetraphenylphosphonium salt of Cu(ptdt)22– 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)22– has a distorted tetrahedral geometry around the Cu atom and the dihedral angle between the planes of the dithiolato ligand is 54.2 °. The crystal structures of Ni(ptdt)2– and Cu(ptdt)22– 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 1.4×10–3 S cm–1 and activation energy of 9.9×10–2 eV.