ROTATIONAL SPECTRUM AND PROPERTIES OF A GAS-PHASE COMPLEX OF MOLECULAR FLUORINE AND HYDROGEN-CYANIDE

Ground-state rotational spectra of three isotopomers (HCN)-N-14 ... F- 2, (HCN)-N-15 ... F-2 and (DCN)-N-14 ... F-2 of a complex formed by hy drogen cyanide and molecular fluorine were observed by using a fast-mi xing nozzle in a Fourier transform microwave spectrometer, Effects of F-F spin-spin and F-spin rotation coupling were observed in the spectr a of (HCN)-N-15 ... F-2 and (HCN)-N-14 ... F-2 and allowed for in the analysis. Spectroscopic constants B-O, D-J and X(aa)(N-14) appropriate to a linear molecule HCN ... F-2 were determined and interpreted in t erms of the geometry and binding strength of the complex, Properties o f several axially symmetric complexes involving the N ... X(2) weak bo nd (X=F or Cl) are compared.