Electronic Structure Insights into the Solvation Behavior of Mg2+ Ion with Cyclic/Acyclic Carbonates

We report on a computational framework to rank-order the solvation behavior of Mg2+ ion in seven common carbonate solvents namely pure carbonate solvents (EC, VC, PC, BC, DMC, EMC, and DEC) and four binary mixtures of carbonates (EC:PC, EC:DMC, EC:EMC, and EC:DEC) using molecular dynamics simulations (MD) and density functional theory. Mg-carbonate complexes were optimized at the M06-2X/6-311++G(d,p) level of theory. The geometry characterization and thermochemistry calculations are fully considered. Based on the metrics of binding energy (ΔEb), enthalpy of solvation (ΔH(sol)), the free energies of solvation (ΔG(sol)) calculated at the M06-2X/6-311++G(d,p) level of theory, and the free energies of solvation resulted from the adaptive biasing force (ABF) method (ΔG(sol)PMF), we find that EC and binary mixture of EC and PC form the best carbonate solvents for interacting with Mg2+ ion. Finally, the nature of the interaction of Mg2+ with carbonate solvents is investigated by Natural bond orbital (NBO) analysis, quantum theory of atoms in molecules (QTAIM) analysis, and Non-covalent Interaction (NCI) plots.