Oligo(metallocene)s containing keto-bridged phospholyl rings

A chiral racemic tris(phosphaferrocene) complex showing two bridging keto functionalities has been prepared diastereoselectively through the elaboration of a single 2,5-diester-substituted phosphaferrocene. The reaction profile involves the intervention of a single trinuclear complex, which contains two phosphametallocene units and an η¹-coordinated phospholyl ligand 9, whose organisation determines the stereochemistry of the final product. This complex evolves smoothly to give a chiral triphosphametallocene (±)-(R,R)-[2,5-(2′-CO₂Me-3′,4′-Me ₂PC₄-FeCp)-(η⁵-Me₂PC ₄)FeCp] 10.