Following previous work on PF
Cl compounds, we report high-level ab initio quantum chemical calculations on PF
Cl, and PF
Cl. Coupled cluster (CCSD(T)) calculations were used to determine the structures and energetics of the various PF
Cl isomers, while generalized valence bond calculations were used to gain a deeper understanding of the factors influencing the structure and energetics of the isomers. Muetterties’ rule, which predicts that more electronegative elements occupy the apical positions in pentavalent phosphorus compounds, is examined in the context of the recoupled pair bonding model, which provides invaluable insights into the bonding, structure, and reactivity of hypervalent compounds. While we found more electronegative fluorine is favored in the apical position in closed-shell PF
Cl, the opposite is true for PF
Cl and two triplet excited state isomers of PF
Cl, all of which are open-shell species.