Computational Study of Hydrogen Bond Interactions in Water Cluster-Organic Molecule Complexes.

We analyzed the interactions present in complexes that acetone, azomethane, dimethylamine, dimethyl ether, methyl acetate, and oxirane form with 39 different (HO) clusters ( = 1-10). A random generation of configurations and a subsequent screening procedure were employed to sample representative interactions. Using quantum chemical computations, we calculated the associated binding energies, which range from -0.19 to -10.76 kcal/mol at the DLPNO-CCSD(T)/CBS level. It was found that the binding energies can be understood in terms of various factors, including the water cluster size, the nature of the organic molecule, and the type of hydrogen bond donor. We find that the most stable complexes often arise from a combination of a strong hydrogen bond plus a secondary interaction between the organic molecule and the water cluster.