The fluorophosphinidene ligand in cyclopentadienyliron carbonyl chemistry: Iron-iron multiple bonding versus higher spin states

► Viable Cp2Fe2(PF)(CO)4 structures have a PF group bridging two CpFe(CO)2 moieties. ► The low energy Cp2Fe2(PF)(CO)3 structures have one PF bridge and one CO bridge. ► The lowest energy Cp2Fe2(PF)(CO)2 structure is a triply bridged triplet spin state. ► Higher spin states are preferred over Fe-Fe multiple bonds in Cp2Fe2(PF)(CO)n (n = 1, 0). ► Cp2Fe2(PF)(CO)n (n = 1, 0) structures are found with separate P and F ligands.