Ab initio MO study of solvated negative alkali atom clusters: [M(H2O)n]− and [M(NH3)n]− (M  Na and Li, n = 1−3)

The structures, stabilities and vertical electron detachment energies (VDEs) of [Na(H2O)n]−, [Na(NH3)n]− and [Li(NH3)n]− (n = 1−3) are investigated by the ab initio MO method at the correlated level. The NaH interactions and hydrogen bonds are important in [Na(H2O)n]−, while the metal-N bonds become essential in stabilizing the [Na(NH3)n]− and [Li(NH3)n]− with increasing n. The size dependence of the VDEs of [Na(H2O)n]− differs from that of [Na(NH3)n]− and [Li(NH3)n]− due to their structural features. In addition, the geometries and VDEs of [Li(H2O)n]− (n = 1−3) are predicted theoretically. The size dependence of their VDEs is similar to that of [Na(NH3)n]− and [Li(NH3)n]− rather than [Na(H2O)n]−.