Mulliken inner complexes [(CH3)(3)NCl](+)center dot center dot center dot F- in pre-reactive mixtures of trimethylamine and chlorine monofluoride: Identification and characterisation by rotational spectroscopy

Ground-state rotational spectra of four symmetric-top isotopomers of a pre-reactive complex formed by trimethylamine and chlorine monofluoride were observed by using a fast-mixing nozzle in a Balle-Flygare microwave spectrometer. The spectroscopic constants B-0, D-J, D-JK, chi(aa)(N-14), chi(aa)(Cl), M(aa)(Cl) and Tr M(Cl) were determined. The observed complex has a structure of C-3 or C-3v symmetry, with the ionic form [(CH3)(3)NCl](+)... F- as the main contributor to its valence-bond description, i.e. the ion Cl+ is largely transferred from ClF to N of trimethylamine on complex formation. Thus, the observed complex is of the Mulliken inner type.