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

Abstract

The reaction between the pentamethylcyclopentadienyl complex [Cp ∗RhCl 2] 2 and disodium maleonitriledithiolate (Na 2 mnt) in CH 2Cl 2 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 1H 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 CH 2Cl 2 and MeCN have been explored, and the redox chemistry is further discussed relative to the results obtained from extended Hückel molecular orbital calculations on monomeric CpRh(mnt).