FTIR spectroelectrochemical investigation of the trans-[Ru(NO)(dimethylglyoximate)(2)Cl] complex: Vibrational characterization of the NO+/0 and Ru-III/II redox couples

This paper deals with the spectroelectrochemical characterization of the Ru-III/II and NO+/o oxidation states of the trans-[Ru(NO)(dmgH)(2)Cl] complex (dmgH = dimethylglyoximate ion). The cyclic voltammograms of the complex in acetonitrile solution exhibited a reversible wave at -0.09 V versus SHE, and two less intense waves at 1.19 and 1.41 V. Visible-UV spectra were recorded at -0.4 and 1.5 V, however, the absorption bands collapsed into a single tail, providing little information on the redox states involved. In contrast, in the FTIR measurements at -0.4 V, the v(NO) peak shifted From 1878 to 1855 cm(-1), without changing the vibrational peaks of the dmgH ligand, indicating an electrochemical process involving the NO+/o redox couple. At 1.5 V, the changes in the vibrational peaks of the NO and dmgH ligands indicated a redox process associated with the Ru-III/II redox-couple. The existence of an open and a cyclic hydrogen bridged configuration was proposed, in order electrochemical waves at positive potentials.