Hydrogen bond and σ‐hole interaction in M2C=S···HCN (M = H,F, Cl,Br, HO,H3C,H2N) complex: Dual roles of C=S group and substitution effect

An ab initio computational study of the dual functions of C?S group in the M₂C?S ··· HCN (M = H, F, Cl, Br, HO, H₃C, H₂N) complex has been performed at the MP2(Full)/aug‐cc‐pVTZ level. The C?S group can act as both the electron donor and acceptor, thus two minima complexes were found for each molecular pairs. The interaction energy of hydrogen bond in the F, Cl, or Br substituted complexes is less negative than that in the corresponding H₂CS one, while the interaction energy of the σ‐hole interaction is more negative. The OH substitution weakens the hydrogen bond, whereas the H₃C and H₂N substitution strengthens it. The σ‐hole interaction in the HO, H₃C, and H₂N complexes is very weak. The substitution effect has been understood with electrostatic induction and conjugation effects. The energy decomposition analysis has been performed for the halogen‐substituted complexes. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012.