Theoretical Study of Beryllium (II) Complexes Using CATIVIC: New Parametric Method

摘要

Calculations of several beryllium complexes {[Be(H_2O)_n]~(2+) (n = 1-4), [BeOH(H_2O_n)]~+ (n = 1-3), and [Be(OH)_2(H_2O),J (n = 1,2)} were carried out to compare different ab initio (density functional theory, MP2) and parametric (PM3(tm), CATIVIC) methods. Results show that the parametric method CATIVIC gives geometries and energies closer to the ab initio geometries than the PM3(tm) method due to the inclusion of the atomic excitation energies of the neutral atoms as well as the ions and to the dependence of the molecular parameters on the system charge. The molecular electronic density analysis of the Be-O bonds shows that the Be-water interaction in the [Be(H_2O)_n]~(2+) complexes can be considered as a closed-shell interaction with a sigma character in the bond while in the [Be(OH)_2(H_2O)_n] complexes the Be-water bond have picharacter.