The role of valence interaction in the 1 : 1 and 1 : 2 complexes between Li + , Na + , Be 2+ , Mg 2+ and CO and N 2 was qualitatively assessed using charge-density-related quantities such as charge transfer, the bond index of the cation-donor atom bond, the valency of interaction and the change in molecular valency calculated at the HF/6–31G ∗ //3–21G level. It has been observed that the relative stability of the complexes can be rationalised on the basis of valence interaction. The molecular hardness parameters have also been calculated. The maximum hardness principle is found to be satisfied in the case of (MCO) n + -(MOC) n+ pairs, and the interaction between (MXY) n + and XY follows the qualitative prediction from the HSAB principle, where M n + is the metal ion and XY is the base.

R. Nirmala

Papers

Ab initio finite perturbation theory calculations of nuclear magnetic-shielding tensors of Li+ and Na+ complexes