Cyclopentadienyl and indenyl complexes of rhodium(I) and rhodium(III) containing chiral diphosphines. X-ray structure of (R)C,(S)Rh-[(η5-C9H 7)Rh(Ph2PCH(CH3)CH2PPh 2)(CH3)]BPh4

Cyclopentadienyl and indenyl complexes of the type (η5-C5H5)Rh(L2) and (η5-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 [(η5-C5H5)Rh(CH3)(L 2)]I and [(η5-C9H7)Rh(CH3)(L 2)]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 31P NMR spectra of the diastereomeric pairs. The crystal structure of (R)C,(S)Rh-[(η5-C9H 7)Rh(Ph2PCH-(CH3)CH2PPh 2)(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 σ-bond of the electrogenerated rhodium-(II) complex. © 1993 American Chemical Society.