The ab initio structures and energies of the isomers of NaAlClnF4_n (n = 0-4) have been calculated at the HF/6-31G* level. Energies for their dissociation into ionic and neutral fragments are presented at the MP2/ 6-31G*//RHF/6-31G* and MP2/6-31+G*//RHF/6-31G* levels. Electron densities of AlCl4-, AlCl2F2-, AlF4-, and their sodium salts are reported and compared with electron densities for Na+Cl- and Na+F-. The agreement between the calculated and experimental equilibrium constants for the exchange reactions between the AlClnF4-n- (n = 0-4) structures is remarkable. The vibrational spectra of AlClnFn- (n = 0-4) anions are calculated and compared with experimental values.