Benzene-water (BZWn (n = 1-10)) clusters.

The gas-phase geometries, binding energies (BEs), infrared spectra and electron density parameters of benzene (BZ)-water (W) clusters (BZW(n), where n = 1-10) have been calculated using Truhlar's meta hybrid functional, M05-2X, employing 6-31+G** basis set. Both basis set superposition error (BSSE) and zero point energy corrected BEs are in close agreement with the previously reported high level ab initio and experimental values. Among all of the BZW(n) clusters, the same with inverted book conformer of water hexamer has the highest BE when compared to all other water clusters. The Bader's theory of atoms in molecule (AIM) provides evidence for the presence of O-H...pi interactions in all of these clusters. In addition, the roles of C-H...O and lone pair...pi (lp...pi) interactions in the stabilization of BZW(n) clusters are also evident from the AIM analysis. The trend in the electron density at the hydrogen bond critical points varies as O-H...pi < lp...pi < C-H...O. Spectral signatures of these clusters further reinforce the existence of weak H-bond between BZ and W(n) clusters. The red shift in all of these clusters ranges from 13 to 95 cm(-1). The results clearly show that the presence of pi-cloud does not affect the H-bonded network of water clusters except in the case of W(6) ring.