Infrared spectra of nitrosyl cyanide and 8 isotopically substituted species. A general harmonic force field determined from experimental data and ab initio calculations

Abstract

Infrared gas phase spectra of ONCN, ONC 15N, ON 13CN, O 15NCN, 18ONCN, O 15NC 15N, O 15N 13CN, 18ONC 15N and 18ON 13CN have been recorded. A general harmonic force field (with six constraints) has been derived based on the assigned fundamental vibration frequencies and checked by calculation of experimental values for centrifugal distortion constants, a Coriolis coupling constant and the inertial defect. The harmonic force field of a fully optimized structure of ONCN as found by the Pulay force method is reported and compared to the experimental force field. No essential disagreements were found.