Abstract
Ab-initio optimized geometries and harmonic force fields were calculated for indene, 1; benzofuran, 2; benzoxazole, 3; benzothiophene, 4; benzothiazole, 5; indole, 6; and indazole, 7, at the HF and B3LYP levels of theory using the 6-31G** basis set. A planar Cs symmetry was assumed in all calculations. The force fields of 1–6 were scaled with respect to the experimental frequencies available in literature. The calculated frequencies confirmed the experimental assignment of these molecules, 1–6. The calculated scale factors were used to calculate vibrational frequencies of 7 and showed possible misassignments in the experimental vibrational frequencies of 7.