Theoretical study of the reactions M++H2O (M = Sr, Ba, La, Hf)

Complete active space self-consistent field (CASSCF) theory followed by multireference second-order Møller–Plesset perturbation-theory (MRMP2) calculations have been performed to analyse the reactions of the H2O molecule with the atomic ions Sr+, Ba+, La+ and Hf+. For the first two ions, only the adduct arising from the electrostatic attraction between the reactants, M+H2O, is stable. For the La+ and Hf+ reactions, the oxidative addition of the H2O molecule to the ion leads to the most stable product. However, a viable path connecting the inserted structure HO–M–H+ with the hydrogen-elimination asymptote MO++H2 has been found for both interactions.