Terminal Aminophosphinidene Complexes of Iron, Ruthenium, and Osmium

The chloroaminophosphido complexes [Cp*M(CO)2{P(Cl)NiPr2}] (1, M = Fe; 2, M = Ru; 3,
M = Os), formed by the reaction of [Cp*M(CO)2]- with iPr2NPCl2, undergo abstraction of
chloride by aluminum trichloride, affording isolable, thermally stable, cationic terminal
aminophosphinidene complexes [Cp*M(CO)2{PNiPr2}][AlCl4] (4, M = Fe; 5, M = Ru; 6, M =
Os). The structures of all three complexes have been determined by single-crystal X-ray
diffraction. The iron complex 4 has historical significance, having been spectroscopically
detected at low temperature in 1984, prior to the description of the first stable η1-phosphinidene complex, but not isolated or structurally characterized.