CYCLOPENTADIENYL AND INDENYL COMPLEXES OF RHODIUM(I) AND RHODIUM(III) CONTAINING CHIRAL DIPHOSPHINES - X-RAY STRUCTURE OF (R)C,(S)RH-[ETA-5-C9H7)RH(PH2PCH(CH3)CH2PPH2)(CH3)]BPH4

Cyclopentadienyl and indenyl complexes of the type (eta5-C5H5)Rh(L2) and (eta5-C9H7)Rh(L2) (L2 = chiral diphosphine) have been synthesized and characterized through multinuclear NMR spectroscopy. These formally planar complexes react with methyl iodide to give the pseudotetrahedral methyl derivatives [(eta5-C5H5)Rh(CH3)(L2)]I and [(eta5-C9H7)Rh(CH3)(L2)]I. The stereochemistry of these complexes, as far as the stereogenic metal center is concerned, is inferred by the difference of chemical shifts of the two phosphorus atoms in the P-31 NMR spectra of the diastereomeric pairs. The crystal structure of (R)C,(S)Rh- [ (eta5-C9H7)Rh(Ph2PCH-(CH3)CH2PPh2)(CH3)]BPh4 has been determined and confirms the above assignment. The electrochemical reduction of the same complex is interpreted in terms of a charge-transfer process followed by the homolytic fission of the Rh-CH3 sigma-bond of the electrogenerated rhodium-(II) complex.