Theoretical study on the nature of S•••H and O•••H hydrogen bonds

Hydrogen bond acceptor ability of sulfur and oxygen has been analyzed in the adducts of dimethyl sulfide ((CH3)(2)S) and dimethyl ether ((CH3)(2)O) with H2O, CH3OH, HCOOH, NH2OH, CH3NH2, NH2NH2, HCONH2, HF and HCl. The stabilization energies have been evaluated using MP2/aug-cc-pVDZ, B3LYP/aug-cc-pVDZ, gaussian2 (G2) and complete basis set (CBS) theoretical levels. The contributors to stabilization energies are explored by employing symmetry adapted perturbation theory analysis, natural bond orbital analysis in addition to molecular orbital methods. Electrostatic component is the major contributor toward stabilization energy in both the type of adducts involving (CH3)(2)S and (CH3)(2)O which has been assigned to secondary electrostatic interactions. The second important contributor to comparable stabilization energies in the two series is the repulsive E-exch component which is relatively higher in adducts of (CH3)(2)O because of the relatively longer proximity of the monomeric units arising from smaller size of oxygen.