Infrared photodissociation spectroscopy of V+(H2O)n (n = 2–8): Coordinative saturation of V+ with four H2O molecules

The V+(H2O)n ions with n = 2–8 are studied by infrared (IR) photodissociation spectroscopy. The IR spectra indicate that H2O molecules are allowed to bind directly to V+ until the completion of a 4-coordinated structure and additional molecules are forced to occupy outer solvation shells. Density functional theory calculations suggest that one empty orbital in V+ (3d4) before coordination can be identified with the 3 d x 2 - y 2 orbital, which provides four sites of lower electron density along the x and y axes. This results in a strong interaction with only four H2O molecules, and thus, a stable square-planar V+(H2O)4 complex.