Rhodium complexes with the chelating and binucleating ligands P(CH2CH2Py)nPh3-n (Py = 2-pyridyl; n = 1,2): structures and fluxional behavior

Inorg Chem. 2000 Feb 21;39(4):705-11. doi: 10.1021/ic990634a.

Abstract

Several rhodium(I) complexes of the type [RhX(CO)(PePy2)], [Rh(diene)(PePy)]+, and [Rh(diene)(PePy2)]+ (PePyn = P(CH2CH2Py)nPh3-n; Py = 2-pyridyl; n = 1, 2) have been prepared. The two former are square planar; the latter are pentacoordinated for diene = tetrafluorobenzobarrelene or norbornadiene (confirmed by X-ray diffraction), but an equilibrium of 4- and 5-coordinate isomers exists in solution for diene = 1,5-cyclooctadiene. The fluxional behavior of all these complexes is studied by NMR spectroscopy. The complex [Rh(NBD)(PePy2)]PF6.Cl2CH2 crystallizes in the monoclinic space group P21/n with a = 8.455(1) A, b = 18.068(3) A, c = 19.729(3) A, beta = 99.658(3)degrees, and Z = 4. The complexes [Rh(diene)(PePy2)]+ react with CO to give the dimeric complex [Rh2(CO)2[P(CH2CH2Py)2Ph]2](BF4)2 with the pyridylphosphine acting as P,N-chelating and P,N-bridging.