Fluorocarbon complexes of transition metals. Part II. Tertiary arsine complexes of rhodium(III) derived from hexafluorobut-2-yne and 3,3,3-trifluoropropyne

Abstract

The complexes RhCl(CO)L₂[L = AsPh₃, AsMePh₂, AsMe₂Ph, AsMe₃, As(p-MeC₆H₄)₃, As(p-FC₆H₄)₃, or AsMe₂(p-MeOC₆H₄)] react with hexafluorobut-2-yne at temperatures between 25 and 100 °C to produce either RhCl(CO)-L₂C₄(CF₃)₄ or RhClL₂C₄(CF₃)₄. In each case the product contains a rhodacyclopentadiene ring. For L = tricyclohexylarsine, little metallocycle is produced but the rhodium(I) complex catalyses the cyclotrimerization of the acetylene. The complexes RhCl(CO)L₂C₄(CF₃)₄ decarbonylate smoothly in refluxing benzene and can be recarbonylated by treatment with carbon monoxide under mild conditions. When L = AsMe₃ or AsMe₂(p-MeOC₆H₄) decarbonylation in the presence of moisture leads to the isolation of RhCl(H₂O)L₂C₄(CF₃)₄. The chloride ligands are also labile and can be removed by treatment with silver nitrate leading to the complexes Rh(NO₃)L₂C₄(CF₃)₄. Reaction of the rhodium(I) complexes with hexafluorobut-2-yne–carbon monoxide mixtures produces L₂Cl[graphic omitted]O [L = AsPh₃, As(p-MeC₆H₄)₃, As(p-FC₆H₄)₃, As(C₆H₁₁)₃]. Reaction of the rhodium(I) complexes with 3,3,3-trifluoropropyne produces the acetylides RhCl(CO)L₂(CCCF₃)₂.