Ab initio Study of the Na+(CO)13 and Na+(N2)13 Complexes

Abstract

The geometries and binding energies of the Na+.(CO)1-3 and Na+.(N2)1-3 have been determined at the level of the CCSD/6-311++G(d, p) method. Our results show that the mono- and di-ligated complexes have linear configurations with the sodium ion carbonyl complexes exhibit larger binding energies due to possess an ion-dipole interaction. A trigonal planar geometry was obtained for the Na+.(N2)3 and Na+.(CO)3 complexes, with the latter having the greatest binding energy of ~ 4 kcal mol-1. The variation in the binding energy between these two types of complexes is due to the fact that the Na+.(CO)1-3 complexes have extra energy that comes from ion...dipole interaction energy. The sequential bond dissociation energies have been determined, and both types of complexes show a similar trend. The observed trend was found to follow the same variation in the ion...quadrupole interaction energies. The contribution of ion-dipole interaction to electrostatic interaction energy is negligible for Na+.(CO)1-3 complexes, accounting for less than 6.5% of the total electrostatic energy. Bond analysis of these complexes shows that sigma-donation of electrons, Clp⟶Na+3s, occurs in the sodium carbonyl ion complexes.