Rotational spectrum of HCN…HI and a comparison of properties in the series HCN…HX (X=F, Cl, Br, I and CN)

Abstract

The ground-state rotational spectra of three isotopomers HC 14N…HI, HC 15N…HI, and HC 14N…DI of the linear hydrogen cyanide-hydrogen iodide dimer have been observed by pulsed-nozzle, F-T microwave spectroscopy and analysed to give rotational constants, centrifugal distortion, nuclear quadrupole and spin-rotation coupling constants. The spectroscopic constants are interpreted in terms of an equilibrium linear geometry with order of nuclei HCN…HI to give r(N…I), K σ and the oscillation angles α av and β av of the HCN and HI subunits. Trends in these properties along the series HCN…HX, where X=F, Cl, Br, CN and I are discussed.