MIGRATION REACTION OF A HYPERVALENT FRAGMENT - BASE-INDUCED MIGRATIONOF A PHOSPHORANE FRAGMENT FROM IRON TO THE CYCLOPENTADIENYL RING IN CP(CO)(2)FE(P(OC(6)ZH(4)Y)(OC(6)H(4)Z)) (Y, Z = NME, NH, O)

Iron phosphorane complexes, Cp(CO)(2)Fe{P(OC6H4Y)(OC(6)H(4)Z)} (Y,Z=NM e,O), react with lithium diisopropylamide (LDA) and then MeI to give { eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z)}(CO)(2)FeMe, showing the first exampl e of migration of a hypervalent phosphorus fragment. The structure of one of the migration products, {eta(5)-C5H4P(OC6H4NMe)(2)}(CO)(2)FeCH2 Ph,was determined by X-ray analysis. Spectroscopic monitoring of the m igration reaction suggests that the reaction is initiated by a proton abstraction on the Cp ring by LDA, followed by migration of the phosph orane fragment to the Cp ring to give {eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z )}(CO)(2)Fe-, which is converted into {eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z )}(CO)(2)FeR by the treatment of alkyl halide. The reaction of Cp(CO)( 2)Fe{P(OC6H4NH)(2)} containing two NH groups with LDA proceeds first w ith NH proton abstraction to give Cp(CO)(2)Fe{P(OC6H4NH)(OC6H4N-)} and then with CP proton abstraction followed by phosphorane migration to give {eta(5)-C5H4P(OC6H4NH)(OC6H4N-)}(CO)(2)Fe-. The addition of MeI f inally led to the isolation of {eta(5)-C5H4P(OC6H4NH)(OC6H4NH)}(CO)(2) FeMe and {eta(5)-C5H4P(OC6H4NH)(OC6H4NMe)}(CO)(2)FeMe.