STRUCTURE, REACTION ENTHALPIES, ENTROPIES, AND FREE-ENERGIES OF CATION-MOLECULE COMPLEXES - A THEORETICAL-STUDY BY MEANS OF THE AB-INITIO COMPLETE BASIS-SET CBS-Q METHOD

Ab initio molecular orbital calculations at the CBS-Q level of theory have been performed for 72 complexes in order to determine the effects of molecular structure on gas-phase basicity toward H+, Li+, and Mg2. It is shown that basicities toward metal cations Li+ and Mg2+ differ considerably from the corresponding gasphase basicities toward H+. Ca lculated interaction energies vary as H+ much greater than Mg2+ > Li+. The relative basicities of the bases studied depend characteristicall y on type of cation and coordination site.