Synthesis, Structure, and Electrochemical Properties of 2,3,4,5-Tetraphenyl-1-Monophosphaferrocene Derivatives

Heteroleptic 2,3,4,5-tetraphenyl-1-monophosphaferrocene [FeCp(η(5)-PC(4)Ph(4))] was obtained at a 62% yield through the reaction of lithium 2,3,4,5-tetraphenyl-1-monophosphacyclopentadienide Li(PC(4)Ph(4)) (1) with [FeCp(η(6)-C(6)H(5)CH(3))][PF(6)]. The structure of 1-monophosphaferrocene 2 and its W(CO)(5)-complex 3 were confirmed by multinuclear NMR and single-crystal X-ray diffraction study and further supported by DFT calculations. Cyclic voltammetry demonstrated that [FeCp(η(5)-PC(4)Ph(4))] 2 has a quasi-reversible oxidation wave. The comparison of the properties of phosphaferrocene 2 with those of W(CO)(5)-complex 3 shows the possibility of changing the coordination type during oxidation.