Geometric and electronic structures of isothianaphthene and thieno[3,4-C]thiophene: A theoretical investigation

Abstract

We present a theoretical (MNDO-SCF-MO and VEH) investigation of the geometry and electronic properties of isothianaphthene (benzo[c]-thiophene) and another thiophene derivative, thieno[3,4-c]thiophene. Our goal is to understand better, at the molecular level, the reasons for a small band-gap in polyisothianaphthene and possibly to guide the organic synthesis towards other interesting polymeric materials. Compared to the parent thiophene molecule, isothianaphthene and thieno[3,4-c]thiophene possess significantly lower ionization potentials and present a strongly conjugated path along their periphery.