Thermodynamic calculations for reactions involving hydrogen halide polymers, ions, and Lewis acid adducts. 3. Systems constituted from Al3+, H+, and Cl-

Semiempirical (MNDO, AM1 and PM3), ab initio (HF/3-21+G(d,p), MP2/3-21+G(d, p), HF/6-311+G(d,p), and MP2/6-311+G(d,p)), and density functional (BVWN/3- 21+G(d,p) and BVWN/6-311+G(d,p)) energy minimization and frequency calculat ions have been carried out on AlCl3, AlCl4-, AlCl2+, HAlCl4, HAlCl3+, and C lHAlCl4-. The same computational set, except for MP2/6-311+G(d,p) frequency calculations, was performed on Al2Cl6 and Al2Cl7-. For ClHAl2Cl7-, only se miempirical calculations, as well as Hartree-Fock and BVWN optimizations us ing the 3-21+G(d,p) and 6-311+G(d,p) basis sets, were carried out along wit h Hartree-Fock frequency determinations. Delta G degrees, Delta H degrees, and Delta S degrees values have been calculated for a number of reactions i nvolving these species along with a variety of ions derived from HCl. Therm odynamic data and equilibrium constants at 298 K are presented for 22 react ions using calculations at the best level, along with a comparison of Delta G degrees values obtained from all molecular orbital methods used.