Bridging H2O and H2S homomeric clusters via H2O-H2S mixed clusters: Impact of the changing ratio of H2O and H2S moieties

Abstract

PESs of H2O-H2S mixed clusters up to tetramer have been investigated to study how replacement of conventional H-bonds by sulfur-centered H-bonds systematically modulates structure and energetic. A total of two, eight, and seventyconformers were obtained for dimers, trimers, and tetramers, respectively. Six types of noncovalent interactions were found in the studied clusters;OH---O, OH---S, SH---O, and SH---S H-bonds, andO---S and S---S interactions. Dimer and trimer are boundsolely by H-bonds, while O---S and S---S interactions along with H-bonds were identified in tetramer. Binding energies and its spread, defined by energy gaps between most and least stable conformers, were found to increase with the number of H2O monomers. Cage structures become preferable overcyclicwith increasing H2S moieties and vice versa. Relative strengths of various types of H-bondsandsignificantly higher cooperativity of classical H-bonds over their sulfur centered counterparts could be potential reasons forstructural and energetic differences.