Successive OH binding energies of M(OH)(n)(+) for n=1-3 and M=Sc, Ti, V, Co, Ni, and Cu

The M(OH)(n)(+) geometries, for n = 1-3, have been optimized and the zero-point energies computed using the B3LYP approach. The calculations show that strong bonds are formed for the early metals, and much weaker bonds are formed for the late metal atoms. The successive OH bond energies have been computed at the CCSD(T) level for n = 1 and 2. The M+-OH bond energies are in good agreement with the guided ion beam results. This implies that the CID values for TiOH+, VOH+, and CoOH+, and the photodissociation value for CoOH+ are accurate, but that the CID values for ScOH+ and NiOH+ are too small. The B3LYP binding energies are found to be in qualitative agreement with the CCSD(T) results. The relative size of the first and second OH binding energies at the B3LYP level disagrees with the CCSD(T) for Sc+, Ti+, and V+ The B3LYP results show that the third OH binding energy for Ti+ and V+ will be large (85 kcal/mol, or more), while for the remaining systems the third OH is electrostatically bound, with a binding energy of only about 30 kcal/mol.