STRUCTURE, HARMONIC FORCE-FIELD AND HYPERFINE COUPLING-CONSTANTS OF NITROSYL CHLORIDE

The pure rotational spectra of five isotopic species of nitrosyl chlor ide were measured using a cavity pulsed microwave Fourier-transform sp ectrometer. Some a-type transitions of all five isotopomers, and some weak b-type transitions of four of these isotopomers were measured in the 4-26 GHz frequency range. Precise values for the rotational consta nts and the quartic centrifugal distortion constants were obtained. Th e rotational constants were used in structure determinations and the c entrifugal distortion constants were used in a refinement of the harmo nic general valence force field. A harmonic central valence force fiel d was also calculated. Hyperfine structure in these transitions arisin g from quadrupole and spin-rotation coupling interactions was also obs erved. Diagonal and off-diagonal quadrupole coupling constants and dia gonal spin-rotation coupling constants of both the chlorine and nitrog en nuclei were determined. The principal quadrupole coupling constants were evaluated and used to calculate the approximate ionic character of the N-Cl bond. The spin-rotational coupling constants were used to calculate the diamagnetic shielding factor for the nitrogen nucleus; t he magnitude of this value indicates a fairly ionic N-Cl bond.