The nature of hydrogen bonds with divalent selenium compounds

Electronic structure of hydrogen bonded complexes of several organoselenium compounds was studied by means of the quantum chemistry methods (HF, DFT, MP2). Energy, geometric and spectral properties of the complexes justify the formation of weak hydrogen bond with selenium atom. However, the detailed analysis of orbital characteristics and the features of electronic distribution by means of topological parameters and integrated atomic properties included in Koch–Popelier criteria of hydrogen bond formation revealed similarities and differences in the properties of complexes with the Se…H bonds in comparison with traditional H-complexes, in which electronegative atoms of the second-row act as proton acceptors. The observed peculiarities of Se…H contacts can be explained by unusual electrostatic repulsion between Se and H atoms opposite to classical N…H or O…H contact and greater stabilization effect of charge transfer in the former. Se…H interaction is also characterized by greater covalence in comparison with conventional H-bonds.