Rhodium(II) trifluoroacetate
Rhodium trifluoroacetate is the chemical compound with the formula. It is used as a catalyst in the synthesis of some organic compounds. The compound and its derivatives have been extensively characterized by X-ray crystallography. It adopts the Chinese lantern structure seen for many dimetal carboxylate complexes. This structure accommodates a Rh-Rh bond, the existence of which explains the diamagnetism of this Rh species. The Rh-Rh distance is 238 pm.
The anhydrous complex is a green volatile solid. It is prepared by dissolving rhodium(II) acetate in hot trifluoroacetic acid:
This reaction expels acetic acid. The Rh-Rh bond is retained.
Reactions
Rhodium trifluoroacetate forms adducts with a variety of Lewis bases. The structures typically have a 2:1 stoichiometry, with one base binding at the "axial" position on each of the two Rh centers:Rhodium trifluoroacetate binds even very weak bases, moreso than does rhodium(II) acetate. It even forms adducts with hexamethylbenzene and with S8.
Rhodium trifluoroacetate catalyzes cyclopropanation of alkenes by diazo compounds: