ClF2: Structure and infrared spectra of a weakly bound triatomic molecule

Abstract

Using sophisticated ab initio methods, the equilibrium structure of the ClF2 radical has been predicted to be bent, confirming previous experimental and theoretical work. The single, double and perturbative triple excitation coupled cluster level of theory along with a triple-ζ plus double polarization basis set gives the geometrical parameters re=1.756 Å and θe=151.8°. At the same level of theory, harmonic vibrational frequencies were predicted to be 536, 243, and 568 cm−1 for the symmetric stretch, bend and asymmetric stretch, respectively. In addition to this high level study of the harmonic vibrational frequencies, theoretical analyses of anharmonic terms have been included in order to help settle the controversy surrounding experimental assignments of the fundamental vibrational frequencies. This research supports Mamantov’s experimental assignment of the bending and symmetric stretching fundamental, over the experimental objections of Prochaska. The vibrational frequency splitting due to 37ClF2 was also studied indicating that only the splitting of the bending and asymmetric stretching modes should be readily observable experimentally. Dipole moments and infrared (IR) intensities were also predicted.