Trinuclear ReFePt clusters with a μ3-phenylvinylidene ligand: synthetic approaches, rearrangement of vinylidene, and redox-induced transformations

Abstract

A series of trinuclear μ₃-vinylidene ReFePt clusters were synthesized by the application of two approaches: (i) reactions of the binuclear RePt μ-vinylidene complexes with Fe₂(CO)₉; (ii) ligand substitution or exchange reactions at the Pt atom in the synthesized ReFePt clusters. The molecular structures of CpReFePt(μ₃-CCHPh)(CO)₅[P(OEt)₃]L [L = CO; P(OEt)₃] were determined by an X-ray diffraction study. The obtained compounds were studied by IR and ¹H, ¹³C and ³¹P NMR spectroscopy. The spectroscopic study revealed that the clusters CpReFePt(μ₃-CCHPh)(CO)₅[P(OEt)₃]L [L = CO; P(OEt)₃] and CpReFePt(μ₃-CCHPh)(CO)₆[P(OPrⁱ)₃] undergo isomerization upon dissolution, resulting in three isomers with different positions of the μ₃-vinylidene ligand over the ReFePt core. The redox properties of the clusters were studied by electrochemical methods. The relatively stable cation-radicals obtained by chemical oxidation of CpReFePt(μ₃-CCHPh)(CO)₆[P(OPrⁱ)₃] and CpReFePt(μ₃-CCHPh)(CO)₅[P(OEt)₃]₂ with ferrocenium tetrafluoroborate were characterized by EPR spectroscopy.