Small heterocyclics as hydrogen bond acceptors and donors: the case of the C2H3XS···NH3 complexes (X = H, F and CH3)

Abstract

B3LYP/6-311++G(d,p) calculations were employed in order to examine the molecular parameters of the C2H3XS···NH3 heterocyclic hydrogen-bonded complexes with X = H, F and CH3. Intermolecular criteria were taken into account when studying the formation of these hydrogen-bonded complexes, such as geometry analysis, charge density quantification and interpretation of the harmonic vibrational spectrum, in which case the appearance of red-shift and blue-shift effects was discussed. It was assumed from the outset that many hydrogen bond types may exist in these systems, and these were investigated using the results of topological integrations from the quantum theory of atoms in molecules (QTAIM) and intermolecular charge transfer calculations using the ChelpG scheme. The proton donor/acceptor behavior of C2H3XS was interpreted in terms of hydrogen bond energies, whose values were corrected using the basis sets superposition error (BSSE) and zero point energy (ZPE).