Solvent effect on some imine-carboxyl complexes

A modified Born equation is used to estimate the solvent effect on the complexation of imine and carboxyl ions. The method is tested for its ability to predict solvation energies by comparing the experimental solvation energies of the fluoroacetic acid and of the fluoroacetate ion to the calculated values. It is found that the method predicts fairly accurate solvation energies. The results of the imine-carboxyl complexes indicate that the solvent stabilizes the ion-pair complex enough to bring its energy of complexation within 1 kcal/mol of the neutral-neutral complex. Thus in solution the two species should coexist. It is also found that the polar solvents make the complexation energy much less negative than in the gas phase, by stabilizing the subspecies preferentially to the complexes.