Activation of perfluoro(methyl vinyl ether) at Rh(<scp>i</scp>) complexes: metal-centered <i>versus</i> phosphine-mediated decarbonylation

This study investigates the reactivity of perfluoro(methyl vinyl ether) [PMVE, CF₂[double bond, length as m-dash]CF(OCF₃)] towards rhodium(i) phosphine complexes. The reaction pathways are characterized by C-O and C-F bond cleavage reactions and decarbonylation steps. On using the complex [Rh(H)(PEt₃)₃] (1), unprecedented reactivity pathways were observed that are distinct from those found for previously studied fluoroolefins. Reactivity of an excess PMVE at Rh is initiated by coordination to the Rh center in 1, followed by its insertion into the Rh-H bond and a β-OCF₃ elimination. This process ultimately results in OCF₃ ligand transformation to give <i>trans</i>-[Rh(F)(CO)(PEt₃)₃] (4) and Et₃PF₂. Reactions of stoichiometric amounts of PMVE with [Rh(H)(PEt₃)₃] (1) or an excess amount of it with [Rh(F)(PEt₃)₃] (6) led to olefin complex formation to yield <i>trans</i>-[Rh(F)(η²-CF₂CFH)(PEt₃)₂] (7) and <i>trans</i>-[Rh(F)(CF(OCF₃)CF₂)(PEt₃)₂] (8), respectively. In contrast, a remarkable insertion into the Rh-F bond at [Rh(F)(CO)(PEt₃)₂] (4) was observed leading to the formation of <i>trans</i>-[Rh(CO)(CF(OCF₃)CF₃)(PEt₃)₂] (5). Decarbonylation of PMVE proceeds not only at Rh, but also <i>via</i> a metal-free, phosphine-mediated process. The latter is characterized by oxidative addition of PMVE at PEt₃ to form the fluorophosphoranes <i>E</i>/<i>Z</i>-(F₃CO)CF[double bond, length as m-dash]CF(PFEt₃), which subsequently convert into Et₃PF₂, CO and presumably tetrafluoroethene.