Rare monomeric structure of CpRh(III) dithiolene complex: Combined ESR and electronic absorption studies on electrochemically generated Rh(II) species

The [CpRhIII(mnt)] (1) (Cp = η5-cyclopentadienyl, mnt = maleonitrile-1,2-dithiolate) was characterized as a rare monomeric structure. The CV of 1 showed a reversible reduction wave which attributed to Rh(II)/Rh(III) couple. UV–Vis spectral measurement during electrolysis using an OTTLE cell indicated that lifetime of electrochemically generated 1radical dot− (Rh(II) species) was only a few seconds. Isotropic (giso = 2.045, Aiso = 1.15 mT) and anisotropic ESR (g1 = 2.173, a1 = 1.85 mT, g2 = 1.982, a2 = 0.98 mT) spectra of 1radical dot− were observed while electrochemical reduction of 1. Both ESR spectra showed hyperfine splittings due to the central Rh (I = 1/2).