THE ROLE OF VALENCE INTERACTION IN SOME CATION-MOLECULE COMPLEXES

The role of valence interaction in the 1 : 1 and 1 : 2 complexes betwe en Li+, Na+, Be2+, Mg2+ and CO and N2 was qualitatively assessed using charge-density-related quantities such as charge transfer, the bond i ndex 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 ha rdness parameters have also been calculated. The maximum hardness prin ciple is found to be satisfied in the case of (MCO)n+-(MOC)n+ pairs, a nd the interaction between (MXY)n+ and XY follows the qualitative pred iction from the HSAB principle, where M(n+) is the metal ion and XY is the base.