DVM-Xα calculations on the ionization potentials of MX k+1 − complex anions and the electron affinities of MX k+1 “superhalogens”

Abstract

The ionization potential (IPs) of the MX k+1 − complex anions BO 2 −, AlO 2 −, NO 3 −, PO 3 −, ClO 4 −, BeF 3 −, MgF 3 −, BF 4 −, AlF 4 −, SiF 5 −, and PF 6 − are calculated by a self-consistent discrete variational Xα method (SCF DVM-Xα). The calculations are carried out both within a numerical Hartree-Fock (HF) basis and within analytical double zeta ones. Valence IPs obtained in both bases coincide with each other within limits of 0.5–1.0 eV. A comparison of the electronic structures of oxygen and flourine containing anions is made. Assuming the first IP of the MX k+1 ion to be approximately equal to the electron affinity (EA) of MX k+1 , estimates of the EAs for the radicals BO 2, AlO 2, NO 3, PO 3, ClO 4, BeF 3, MgF 3, BF 4, AlF 4, SiF 5, and PF 6 are obtained. It is shown that EA of the MX k+1 should be low if the highest occupied MO of the corresponding MX k+1 − anion contains AOs of the central atom (or in terms of localized MOs the central atom possesses a lone pair). In contrast, if the highest occupied MO of an anion is formed from ligand AOs only (or in terms of localized orbitals the central atom does not possess any lone pairs) the EA of a radical should be large. The estimated EAs of the MX k+1 radicals are used for a comparison between possibilities of heterolytical and homolytical channels of the L-MX K+1 bond destruction in complex salts of alkali metals.