Symmetrization of Bromobis(polyfluorophenyl)thallium(III) compounds with copper powder

Abstract

Reaction of bromobis(polyfluorophenyl)thallium(III) compounds, R₂TlBr (R = C₆F₅, p-HC₆F₄, m-HC₆F₄ or 3,5-H₂C₆F₃) and (C₆F₅)₂TlOH, with copper powder in boiling 1,4-dioxan (diox) or diethyl ether gave the corresponding tris(polyfluorophenyl)thallium(III) compounds, which were isolated as the complexes R₃Tl,diox. By contrast, the derivatives R₂TlBr (R = o- HC₆F₄, 3,6-H₂C₆F₃ or Ph) failed to react, and (C₆F₅)₂TlBr was decomposed by copper powder in boiling toluene yielding decafluorobiphenyl. Formation of tris(polyfluorophenyl)thallium(III) compounds is considered to occur via polyfluorophenylcopper(I) intermediates. Treatment of (C₆F₅)₂TlBr with pentafluorophenylcopper in dioxan gave (C₆F₅)₃Tl,diox. The new bromobis-(polyfluorophenyl)thallium(III) compounds, R₂TIBr (R = p-HC₆F₄, m-HC₆F₄, o-HC₆F₄, 3,5-H₂C₆F₃ or 3,6- H₂C₆F₃), were prepared by reaction of thallic chloride with the appropriate Grignard reagents.