STRUCTURES AND ENERGETICS OF ZN(NH3)(N)(2+) (N=4-6) - COORDINATION-NUMBER OF ZN2+ BY AMMINE

Abstract

From ab initio studies of Zn(NH3)(n)(2+) complexes (n=4-6), their various minimum energy structures have been identified for the first time. The hexa-ammine-Zn(II) complexes with the coordination numbers (N-c) of 4 to 6 have almost the same enthalpies. But, owing to the entropy effect the complex with N-c=4 has the lowest free energy. Nevertheless, the structural stabilities of these complexes are not so different; thus, the N-c may vary between 4 and 6 according to given molecular environments, though N-c=4 is the most favored. This is in accord with the statistical analysis of the X-ray data of the Zn(II) complexes coordinated by nitrogen-containing ligands.