Ab initioand DFT studies on the structures, binding energies and nature of bonds in X2Y3metal clusters (X+=Li+,Na+andK+; ${\rm Y}_{3}^{2-} = {\rm Zn}_{3}^{2-}, {\rm Cd}_{3}^{2-}$ and ${\rm Hg}_{3}^{2-}$)

Abstract

A comprehensive theoretical study on the structure and stability of linear and triangular isomers of anionic clusters of zinc, cadmium and mercury [Formula: see text] and their binding with one and two alkali metal cations ( X+= Li+, Na+, K+) has been investigated at the density functional (BP86 and B3LYP) and ab initio (MP2, MP4and coupled cluster single and double (CCSD)) methods. The results showed that in all cases, the triangular geometry with D3hsymmetry is more stable than linear one. The calculated values of interaction energies (IE) between [Formula: see text] anions and two X+cations, Wiberg bond indices (WBI) and the electron densities at bond critical points (BCP), ρ(BCP), for Y–X bonds show that among all complexes investigated here at all levels of theory Zn3Li2and Hg3K2have the largest and the smallest values of IE, WBI and ρ(BCP), respectively. The natural charges of the atoms and WBI involved in the bonding as well as the global value of the charge transfer ΔQ from [Formula: see text] to X+cation in X2Y3clusters, evaluated through natural population analysis, confirmed that covalent contribution in Y–X bond formation increases from K+to Li+. Also the energy decomposition analyses (EDA) were used to detect the nature of interaction in the complexes. The results confirmed that the contribution of electrostatic interactions in present complexes is almost more than 70%.