Reductive Activation of Carbon−Fluorine Bonds in Perfluoroalkyl Ligands:  An Unexpected Route to the Only Known Tetrafluorobutatriene Transition Metal Complex:  Ir(η⁵-C₅Me₅)(PMe₃)(2,3-η²-CF₂CCCF₂)

Abstract

Six-electron reduction of the perfluoro-sec-butyl ligand in Cp*Ir(PMe3)I(C4F9) with sodium naphthalenide affords the first known example of a transition metal complex of tetrafluorobutatriene, Cp*Ir(PMe3)(C4F4). The free ligand is a highly unstable compound. The compound has been completely characterized by a single-crystal X-ray diffraction study; the center coordinated double bond shows significant elongation, and the flanking fluoroalkenes show significant shortening, as compared to the dimensions in the free ligand.