ROTATIONAL SPECTRA AND GEOMETRIES OF THE GAS-PHASE DIMERS (CH4,HF) AND (CH4,HCL)

The rotational spectra of five isotopomers of the dimer (CH4,HCl) and two isotopomers of the dimer (CH4,HF) have been investigated by the pulsed-nozzle FT microwave technique. Detailed consideration of the spectroscopic constants allows the conclusion that the HCl complex has an effective C3ν geometry of the type CH4...HCl with a single hydrogen bond and internal rotation of the CH4 subunit while the interaction in (CH4,HF) is of the two-centre type, involving bonds CH...F and C...HF, which appears effectively to quench the internal rotation. © 1990.