Solvation of the Cl - ·H 2 O Complex in CCl 4 Clusters: The Effect of Solvent-Mediated Charge Redistribution on the Ionic H-Bond

The OH stretching bands associated with the ionic H-bond in the Cl - ·H 2 O complex are found to dramatically shift toward higher energy upon complexation with carbon tetrachloride molecules in a size selected photofragmentation study of the Cl - ·H 2 O·(CCl 4 ) n, 1 ≤ n ≤ 5, clusters. The large sequential shifts (80−100 cm -1 /CCl 4 ) associated with addition of the first few molecules effectively “tune” the OH stretch v = 1 level through a Fermi resonance with the v = 2 level of the intramolecular bending vibration. By the addition of the fifth molecule, the large red-shift displayed by the bare complex (577 cm -1 relative to isolated water) is reduced by a factor of 2. We discuss the origin of these effects in the context of charge redistrubition from chloride to the surrounding solvent molecules.