Products from the reaction of trans-oxotrihalogenobis(triphenylphosphine)rhenium(V) with carboxylic acids, and related compounds

Abstract

By heating trans-ReOX₃(PPh₃)₂ with a variety of carboxylic acids or their anhydrides we have isolated not only the known compounds ReX₄(PPh₃)₂ and Re₂Cl₂(R·CO₂)₄ but also the new series of carboxylato-complexes, Re₂Cl₃(R·CO₂)₂(PPh₃)₂, Re₂OX₅(R′·CO₂)(PPh₃)₂, and Re₂Br₂(R·CO₂)₄(X = Cl or Br, R = alkyl, R′= alkyl or aryl). The relative proportions of these compounds depend, inter alia, on the duration of heating, the amount of oxygen present, and the strength of the acid used. Convenient preparative routes to the compounds ReCl₄(PPh₃)₂ and Re₂Cl₂(R·Co₂)₄ are described.