Formation of iron-fluorophosphorane complexes (eta(5)-C5H5)(CO)LFe{P(OPh)(n)F4-n} (L = CO, P(OPh)(3); n = 0, 1) and (eta(5)-C5H5)(CO)(2)Fe{Pb(OC6H4NMe)F-2}. Nucleophilic attack of F- toward a trivalent phosphorus atom coordinated to a transition metal

The reaction of a phosphite complex, [Cp(CO)(2)Fe{P(OPh)(3)}]PF6, with Et4N F in CH2Cl2 at room temperature yielded a mixture of metallafluorophosphora nes, Cp(CO)(2)Fe(PF4) (1) and Cp(CO)(2)Fe{P(OPh)F-3} (2). Similar phosphite complexes [Cp(CO)Fe{P(OPh)(3)}(2)]PF6 and [Cp(CO)(2)Fe{P(OC6H4NMe)(OC6H4NM eH)}]PF6 also reacted with F- to form Cp(CO){P(OPh)(3)}-Fe(PF4) (3) and Cp( CO)(2)Fe{P(OC6H4NMe)F-2} (4), respectively. The P-31 and F-19 NMR studies o f these metallafluorophosphoranes revealed that pseudorotation around the h ypervalent phosphorus center takes place readily in 1 and 3, whereas it mar ginally occurs at room temperature in 4, but not in 2 even at elevated temp erature. The difference in the energy barrier of the rotation process was i nterpreted in terms of the apicophilicity of the substituents on the phosph orane phosphorus.