Rotational spectrum of the nitrogen trifluoride–chlorine monofluoride complex and the inductive effect of groups R=CH3, H, F on R3N/ClF interactions

Rotational constants B0, centrifugal distortion constants DJ and DJK, and nuclear quadrupole coupling constants χaa(14N) and χaa(Cl) were determined by pulsed-nozzle, Fourier transform microwave spectroscopy for the isotopomers F314N⋯35ClF and F314N⋯37ClF of a complex formed by nitrogen trifluoride and chlorine monofluoride. The distance r(N⋯Cl) and the intermolecular stretching force constant kσ for this symmetric-top species are compared with those of several axially symmetric complexes B⋯ClF in which a nitrogen atom of the base B interacts with ClF. In particular, it is shown that r(N⋯Cl) decreases along the series R3N⋯ClF, where R=F, H or CH3, while kσ increases dramatically.