A theoretical study of HClO3 isomers

Ab initio quantum chemical calculations on normal and hypervalent structures of the HClO3 species have been performed. Four minima were located at the MP2/6-31G(d) level, after many connectivities were investigated. Geometries and frequencies were determined at the QCISD/6-311G(2d, 2p) level. Single point energy calculations using QCISD(T) with larger basis sets indicate that the lowest energy structure is hypervalent HOClO2, upon inclusion of f functions. Also, relative energies computed with the G2 method are in good agreement with the QCISD(T) results with large basis sets.