Ab initio calculations of chloride complexes of Au, Hg, Tl, Pb, and Bi in anomalous oxidation states (2S1/2 electron state)

Ab initio calculations of chloride complexes of Au, Hg, Tl, Pb, and Bi in anomalous oxidation states (²S_1/2 electron state) were carried out by the Becke-Lee-Yang-Parr density functional method using the Dunning-Hay LanL2DZ basis set. Optimum geometric parameters and electronic characteristics of MCl _n (H₂O) _m ⁿ (n=1–4 andm=0,4,5) complexes were determined. In each of the considered series the spin, population on the central metal atom decreases as its atomic number increases. The energy of transition of the unpaired electron to the lowest unoccupied MO decreases in the same order. The unpaired electron occupies an orbital that is mostly a linear combination of the s-orbital of the metal atom and the p-orbital of the Cl atom (the antibonding σ-orbital of the M−Cl bond). Distinctions in the changes in spectral properties of aquacomplexes and chloride complexes in isoelectronic series, observed as the degree of oxidation of the metal atom increases, were explained. The results of calculations are in agreement with the experimental data obtained by ESR and optical spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1049–1055, June, 1999.