Carbon–fluorine and –hydrogen bond activation and carbon–carbon bond formation in η5-pentamethylcyclopentadienyl-rhodium and -iridium phosphine complexes; crystal structures of [M(η5-C5Me5)Cl{(C6F5)2PCH2CH2P(C6F5)2}]+BF4–(M = Rh or Ir)

Abstract

The reaction between [{M(η⁵-C₅Me₅)Cl(µ-Cl)}₂](M = Rh or Ir) and (C₆F₅)₂PCH₂CH₂P(C₆F₅)₂(dfppe) in refluxing benzene yielded the cationic species [M{η⁵-C₅Me₃[CH₂C₆F₄P(C₆F₅)CH₂]₂-1,3}Cl]⁺ in which two C–F and two C–H bonds have been cleaved and two C–C bonds formed; HF is also produced. The complexes [M(η⁵-C₅Me₅)Cl(dfppe)]⁺BF₄^–(M = Rh or Ir), which have not undergone C–F bond activation, were formed by treatment of [{M(η⁵-C₅Me₅)Cl(µ-Cl)}₂] with NH₄BF₄ and dfppe, and have been structurally characterized by X-ray crystallography. Activation of the C–F bonds in these complexes is induced by thermolysis in refluxing ethanol. The reaction between [{M(η⁵-C₅Me₅)Cl(µ-Cl)}₂](M = Rh or Ir) and dfppe in refluxing ethanol yielded a mixture of the cations [M(η⁵-C₅Me₅)Cl(dfppe)]⁺, [M{η⁵-C₅Me₃[CH₂C₆F₄P(C₆F₅)CH₂]₂-1,3}Cl]⁺ and, where M = Rh, the singly C–F bond-activated species [Rh{η⁵-C₅Me₄CH₂C₆F₄P(C₆F₅)CH₂CH₂P(C₆F₅)₂}Cl]⁺.