On the geometry and inversion process of PF 3+· (X̃ 2A 1)

Abstract

Geometries of PF 3, PF 3 +· 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, PF 3 +· has, in its ground state X̃ 2A 1, a pyramidal geometry and undergoes inversion following an edge-inversion mechanism through T-shaped C 2v structures. Our calculations suggest the barrier heights of 225 kJ/mol for PF 3 and 168 kJ/mol for PF 3 +·. Although these barriers to inversion are significantly smaller than those recently reported in the literature, the barrier of PF 3 +· is still greater than the value of the v 2 frequency of this cation, supporting this pyramidal character.