Tris(pentafluorophenyl) neutral and anionic five-co-ordinate complexes of rhodium(III). Crystal structures of [Rh(C6F5)3(PEt3)2] and [Rh(C6F5)3(AsPh3)2]

Abstract

The binuclear compound [P(CH₂Ph)Ph₃]₂[{Rh(µ-Cl)(C₆F₅)₃}₂](1) has been prepared by reaction of HCl with [P(CH₂Ph)Ph₃]₂[Rh(C₆F₅)₅](2) in methanol. Treatment of (1) with thallium(I) acetylacetonate has given the anionic complex [P(CH₂Ph)Ph₃][Rh(acac)(C₆F₅)₃](acac = acetylacetonate). Addition of neutral ligands L to (1) yields anionic derivatives of the type [P(CH₂Ph)Ph₃][RhCl(C₆F₅)₃L][L = pyrazole (Hpz), pyridine (py), PPh₃, AsPh₃, or CO](3)–(7) and the reaction of (1) with AgClO₄ in the presence of 2 mol of neutral ligands gives rise to neutral compounds [Rh(C₆F₅)₃L₂][L = P(OMe)₃, PPh₃, PEt₃, AsPh₃, py, Hpz, 4-methylpyrazole, or 3,5-dimethylpyrazole](8)–(15). The crystal structures of the complexes [Rh(C₆F₅)₃(PEt₃)₂](10) and [Rh(C₆F₅)₃(AsPh₃)₂](11) have been determined by X-ray diffraction methods. Both structures consist of very flattened square-pyramidal complexes in which two C atoms from C₆F₅ groups and two P from PEt₃ ligands [(10)], or two As from AsPh₃ ligands [(11)], occupy the basal positions, whereas the third C atom from a C₆F₅ ligand lies at the apex.