Solubility and solvation of carbon dioxide in the molten Li2CO3/Na2CO3/K2CO3 (43.5 : 31.5 : 25.0 mol-%) eutectic mixture at 973 K - II. Theoretical part

A theoretical study of the structure and stability of the dicarbonate ion h as been performed at the Hartree-Fock, MP2, and QCI/SD levels. A flexible 6 -31+G(d) basis set was used to allow for the diffuse electron density appea ring in the anions, A stable anion corresponding to two CO2 entities covale ntly bound to a central oxygen has been found. The formation reaction start ing from the carbonate anion and carbon dioxide has also been studied. Its thermodynamic features favour the formation of the dicarbonate anion, which in turn may account for the impressive solubility of carbon dioxide in car bonate melts.