On the spectroscopic consequences of different tunnelling mechanisms in non-rigid RPF4 molecules (R = CF3)

Previous experimental results indicate that the CF3 group in CF3PF4 occupies an equatorial position in the ground state structure and that the less stable axial structure may be reached via a polytopal rearrangement. Such a dynamic behaviour differs drastically from that of CH3PF4 where only permutational rearrangements occur. In the present paper we assume a small distortion of the idealized PF5 geometry by the CF3 ligand. In such a case, a description in terms of permutational and polytopal pathways belonging to the same idealized mode is justified. We obtain theoretical modifications of the rotation-vibration spectra of the axial and equatorial configurations of CF3PF4 due to various permutational and polytopal tunnellings. These modifications are characteristic of the pathways and could be used to discriminate between them. © 1980 Taylor and Francis Ltd.SCOPUS: ar.j