A computational study of the hydride affinities of Group I and Group II metals

A computational study of the hydride affinities of Group I and Group TI metals is described. Hydride affinities are reported for MH and M (M = Li, Na) and MH2 and MH (M = Be, Mg). Calculated hydride affinities range from similar to 35 kcal mol(-1) for Na to similar to 67 kcal/mol for BeH, The unusually high hydride affinity for BeH is shown to reflect the high Be-H bond energy in BeH2. Where comparisons are possible, the results obtained using the MPI, MP4, BLYP, and B3LYP methods with a 6-311++G(3df,3pd) basis set are in good agreement with experimental of high level theoretical values. Hydride affinities calculated using the G2 approach are too high because of the G3 energy for hydride ion. More reasonable values are obtained from the G2 calculations using the exact energy for the hydride ion. (C) 2000 Elsevier Science B.V.