On the geometry and inversion process of PF3+· (X̃ 2A1)

Geometries of PF3, PF3+· and the respective energy barriers to inversion are calculated using both MO (MP2, QCISD(T) and CISD) and DFT (B3LYP) methods. Various points on the potential energy surfaces are explored by means of vibrational analyses. Similar to the neutral species, PF3+· has, in its ground state X̃ 2A1, a pyramidal geometry and undergoes inversion following an edge-inversion mechanism through T-shaped C2v structures. Our calculations suggest the barrier heights of 225 kJ/mol for PF3 and 168 kJ/mol for PF3+·. Although these barriers to inversion are significantly smaller than those recently reported in the literature, the barrier of PF3+· is still greater than the value of the v2 frequency of this cation, supporting this pyramidal character.