Synthesis of 2,5-Difunctional Phosphaferrocenes

The reaction of FeCl2 with a 1:1 mixture of 2,5-diacylphospholides and Cp*Li in the presence of ZnCl2 affords 2,5-bis(RCO)phosphaferrocenes when R = OEt, Ph and the tetrafunctional 1,1′-diphosphaferrocene when R = tBu. We explain these results by a combination of two effects: the push−pull stabilization of the ferrocene structure by Cp* (donor) and phospholide (acceptor) and the classical steric protection of the η5 complexes by bulky α-substituents.