Redox investigation and X-ray diffraction structure of the dimeric rhodium maleonitriledithiolate complex [Cp*Rh(mnt)](2). Confirmation of bridging and chelating mnt ligands in the solid-state structure

The reaction between the pentamethylcyclopentadienyl complex [Cp*RhCl2](2) and disodium maleonitriledithiolate (Na(2)mnt) in CH2Cl2 solvent affords the mnt-substituted compound Cp*Rh(mnt) in moderate yield. Cp*Rh(mnt) has been isolated and characterized in solution by IR and H-1 NMR spectroscopy, and by isopiestic molecular weight measurements, which confirm the monomeric nature of this complex. However, the solid-state structure has been re-determined by X-ray diffraction analysis, revealing the presence of a dimeric structure for Cp*Rh(mnt) that possesses both bridging and chelating mnt ligands. The relationship of dimeric [Cp*Rh(mnt)](2) to the previously reported monomeric structure for Cp*Rh(mnt) [R. Ziessel, M.-T. Youinou, F. Balegroune, D. Grandjean, J. Organomet. Chem. 441 (1992) 143] is discussed. The electrochemical properties of Cp*Rh(mnt) in CH2Cl2 and MeCN have been explored, and the redox chemistry is further discussed relative to the results obtained from extended Huckel molecular orbital calculations on monomeric CpRh(mnt). (C) 1997 Elsevier Science B.V.