227000-04-6Relevant articles and documents
Chemistry of 2-(arylazo)phenolate complexes of ruthenium. Synthesis, structure and reactivities
Sui, Kanchana,Peng, Shie-Ming,Bhattacharya, Samaresh
, p. 631 - 640 (1999)
A group of six ruthenium(III) complexes of type [Ru(acac)(L)2], where acac = acetylacetonate anion and L=2-(arylazo)-4-methylphenolate anion or 1-(phenylazo)-2-naphtholate anion, have been synthesized and characterized. Structural characterization of a representative complex, where L=1-(phenylazo)-2-naphtholate anion, shows that the azophenolate ligands are coordinated as N,O-donor ligands forming six-membered chelate rings. The complexes are paramagnetic (low-spin d5, S=1/2) and show rhombic ESR spectra in 1:1 dichloromethane-toluene solution at 77 K. In carbon tetrachloride solution, these complexes show intense LMCT transitions in the visible region together with weak ligand-field transitions in the near-IR region. All the complexes display two cyclic voltammetric responses, a ruthenium(III)-ruthenium(IV) oxidation in the range of 0.83 to 1.03V vs SCE and a ruthenium(III)-ruthenium(II) reduction in the range of -0.24 to -0.52 V vs SCE. Formal potentials of both the couples correlate linearly with the Hammett constant of the para substituent in the arylazo fragment of the 2-(arylazo)-4-methylphenolate ligand. The ruthenimn(IV) and ruthenium(II) congeners of the [RuIII(acac)(L)2J complexes have been generated by chemical or electrochemical methods and they have been characterized by electronic spectroscopy and cyclic voltammetry.
