GEOMETRIES, FORCE-FIELDS, AND VIBRATIONAL ASSIGNMENTS OF DEWAR BENZENE AND DEWAR PYRIDINE

The geometries of Dewar benzene and Dewar pyridine were fully optimized by restricted Hartree-Fock theory and the 6-31G* basis set. Reference geometries for force field calculations were obtained by systematic empirical corrections. The ab initio force fields, after empirical scaling, yield frequencies which are in good agreement with experiments. On the basis of the calculations, some uncertainties in the experimental assignments of the fundamental frequencies of Dewar benzene were resolved, and assignments for the observed matrix IR frequencies of Dewar pyridine were given for the first time. This study demonstrates again the value of the scaled quantum mechanical (SQM) force field method.