Mixed-valence pyrazolate rhodium complexes. Molecular structure of [(C5Me5)ClRhCl(pz)Rh(tfb)]·CH2Cl2(Hpz = pyrazole; tbf = tetrafluorobenzobarrelene)

Abstract

Mixed-valence rhodium(III)–rhodium(I) complexes containing pyrazolate(1–)(pz) and/or chlorine groups as bridging ligands have been prepared. The structure of [(C₅Me₅)ClRhCl(pz)Rh(tfb)]·CH₂Cl₂[tfb = tetrafluorobenzobarrelene (5,6,7,8-tetrafluoro-1,4-dihydro- 1,4-ethenonaphthalene)], prepared by reacting [Rh(C₅Me₅)Cl₂(Hpz)] with [Rh(acac)(tfb)][acac = acetylacetonate(1–)], has been determined by X-ray diffraction methods. This heterobridged complex is composed of two rhodium atoms (Rh^III and Rh^I) bridged by a chlorine atom and a pyrazolate group. The rhodium–rhodium distance is 3.715(2)Å. The preparation and properties of the homobridged neutral and cationic complexes [(C₅Me₅)XRh(pz)₂RhL′₂][X = Cl, L₂′= tfb, cycle-octa-1,5-diene (cod), (CO)₂, or (CO)(NCBu^t); X = pz, L₂′= tfb], [(C₅Me₅)L″Rh(pz)₂RhL₂′][ClO₄][L″= pyridine (py), McCN, or Hpz, L₂′= tfb; L″= py, L′= CO], and [(C₅Me₅)(Hpz)RhCl₂Rh(tfb)][ClO₄] are reported.