A Gaussian-3 (G3) theoretical study of the interactions between alkali metal cations and polyhydroxyl ligands

Ab initio molecular orbital calculations at the G3(GCP) level were conducted for the alkali cation–alcohol complexes (M+–L, where M+=Li+, Na+, and K+; L=methanol, ethylene glycol, propan-1,2-diol, propan-1,3-diol and propan-1,2,3-triol). In general, these cations maximize the number of M+⋯O interactions with the ligands. The role of intramolecular hydrogen bonding, ligand polarizability, ligand deformations, number of M+⋯O interactions and the M+⋯O distances in governing M+–L affinities was discussed. The computationally less expensive G2(MP2,SVP)–FC/ASC models were found to yield affinities in good agreement against the G3(GCP) benchmark, but the agreement deteriorates somewhat with increasing number of M+⋯O interactions.