On the enthalpy of formation of thiophene

Abstract

Thiophene is an important contaminant of petroleum-derived fuels, and it also plays an important role in molecular electronics. We have calculated the enthalpy of formation of thiophene employing the CCSD(T) methodology and the cc-pV(X + d)ZX = T,Q,5 basis sets. At the CCSD(T)/CBS limit and including corrections for scalar relativistic effects, anharmonic effects, spin–orbit and core-valence correlation effects, the estimated enthalpy of formation is 25.15-1+0.5 kcal/mol. Our estimation is 2.3 kcal/mol lower than the experimental value. The discrepancies between experiment and theory are expected to be increased if higher-order correlation effects are taken into account. Thus, a new determination of the experimental value is highly recommended. Finally, we discuss the problems faced to make this estimation, in particular the determination of accurate Zero-point energy corrections and the evaluation of core-valence correlation effects.