Theoretical investigation of the conformational behavior of 2,2′-bithiophene

Quantum-chemical calculations are used to investigate the conformational structure of 2,2′-bithiopehen taken as a model for polythiophene. The geometries of the optimal syn and anti conformations are fully optimized at the ab initio level using a double-zeta polarized (DZP) basis set. The energetics of the torsion around the inter-ring single bond are determined, within the rigid-rotor approximation, on the basis of these optimized geometries. The effects of electron correlation are analyzed with M∅ller-Plesset perturbation theory (MP2).