Abstract
Optimized geometry, vibrational frequencies and IR absorption intensities were calculated for the C
i(1) conformation of 18c6. Optimized geometry was compared with the experimental geometry and that of the C
i(2) conformation of 18c6. The C
i(1) conformation is more planer than the C
i(2) conformation of 18c6, which provides an explanation that free 18c6 in the crystal phase has a C
i(1) conformation. Vibrational frequencies were scaled using an unvaried one-scale-factor scaling of 0.928. Calculated vibrational frequencies were compared with the experimental vibrational frequencies. The root-mean-square deviation of the difference between the calculated and experimental frequencies was only 15 cm
−1. This excellent agreement between the calculated and experimental frequencies is an indication of the proper assignment of the fundamental vibrational frequencies of the C
i(1) conformation of 18c6.