Thiophene-substituted nickel dithiolene complexes. Precursors for low band gap conjugated metallopolymers

Abstract

A series of electrochemically polymerizable Ni dithiolene complexes have been prepared and their electrochemical and spectroscopic properties have been characterized. Three thiophene-substituted complexes were anodically polymerized to give polymer films whose electrochemical properties correlated well with their predicted structures. Thus, a complex with two thiophene substituents in one dithiolene ligand [cis-1,2-di(2′-thienyl)-1,2-ethenedithiolene] gave a polymer with electrochemistry characteristic of a poly(dithienylenevinylene), while a complex with one thiophene substituent on each dithiolene ligand [cis-1-(2′-thienyl)-2-phenyl-1,2-ethenedithiolene] gave a polymer with electrochemistry characteristic of a coordination polymer. A polymer prepared from a complex with four thiophene substituents {bis[cis-1,2-di(2′-thienyl)-1,2-ethenedithiolene]nickel} also gave electrochemistry characteristic of a poly(dithienylenevinylene), indicating that it contained extended poly(dithienylenevinylene)-like chains. A cathodically polymerizable complex, bis[cis-1,2-di(4-bromophenyl)-1,2-ethenedithiolene]nickel, is also reported.