Pyridine-CF4: A Molecule with a Rotating Cap

The rotational spectrum of pyridine-CF4 has been investigated by molecular beam Fourier transform microwave spectroscopy in a supersonic expansion. The CF4 moiety is located as a cap over the pyridine nitrogen, and the two parts are freely rotating with respect to each other. For this reason, in a first approximation, in the m = 0 state only the pyridine ring is rotating along the a-axis, and the value of rotational constant A' is nearly the same of the constant A of isolated pyridine. The (NCCF4)-C-..., distance is 3.372(1) angstrom. The dissociation energy has been estimated, from the centrifugal distortion, to be ca. 10 kJ/mol.