14N quadrupole coupling constants and 14N and 19F spin–rotation coupling constants of nitrosyl fluoride, FNO, and nitryl fluoride, FNO2

Abstract

High-resolution pure rotational spectra of nitrosyl fluoride, FNO, and nitryl fluoride, FNO₂, have been measured using a cavity pulsed microwave Fourier-transform spectrometer. The samples were prepared using a pulsed electric discharge through precursor substances, with the discharge apparatus mounted as part of the pulsed nozzle of the spectrometer. Nuclear quadrupole and magnetic hyperfine structures due to ¹⁴N and ¹⁹F have been resolved for both molecules, and precise values for the nuclear quadrupole and spin–rotation coupling constants have been obtained. The ¹⁴N quadrupole coupling constants of FNO₂ have been rationalized in terms of a σ-withdrawal of electron density from NO₂ towards F. This view is corroborated by the magnetic shielding estimated from the F spin–rotation constants.