Ab initio quantum chemical calculations of geometry and vibrational frequencies of chlorine heptoxide

Ab initio force fields for the vibrations of Cl2O7 in its ground electronic state have been determined at the Hartree-Fock level using the 6-31G* basis set. The calculated geometries of Cl2O7 at HF/6-31G* and MP2/6-31G* have been compared with the corresponding X-ray crystallographic structure. The calculated vibrational frequencies of Cl2O7 are discussed in comparison to those determined from experiment and to the corresponding quantities for some similar molecules of the type ClO3-O-X (X is F, Cl, Br, H).