An electrochemical investigation on the reduction path of the arene complexes [CpM(arene)]2+ and [(η-9-SMe2-7,8-C2B9H10)M(arene)]2+ (M=Rh, Ir)

ArticleinJournal of Solid State Electrochemistry 11(12):1643-1653 · November 2007with4 Reads
Impact Factor: 2.45 · DOI: 10.1007/s10008-007-0324-2

    Abstract

    The reduction behavior of the isoelectronic complexes [CpMIII(η6-C6R6)]2+ (M=Rh, Ir; R=H, Me) and [(η-9-SMe2-7,8-C2B9H10)MIII(η6-C6R6)]2+ (M=Rh, Ir; C6R6 = C6H6, C6H5OMe, C6H3Me3) has been studied by cyclic voltammetry and controlled potential coulometry in acetonitrile and propylene carbonate at 253
    and 298K, respectively. The extent of chemical reversibility of the pertinent sequences Rh(III)/Rh(II)/Rh(I) and Ir(III)/Ir(I)
    is highly dependent on both the nature of the solvent and the intrinsic electronic properties of the arene substituents. The
    arene η6 coordination makes the derivatives in their lower oxidation states notably short lived, even if, in some cases, the use of
    propylene carbonate improves their stability or causes the increase in their lifetimes before changing the arene coordination
    from η6 to η4. Cations [(η-9-SMe2-7,8-C2B9H10)M(η6-C6R6)]2+ were obtained by the bromide abstraction from [(η-9-SMe2-7,8-C2B9H10)MBr2]2 with Ag+ in the presence of benzene and its derivatives. The structure of [(η-9-SMe2-7,8-C2B9H10)Ir(η6-C6H5OMe)](BF4)2 was determined by X-ray diffraction.