Keene, F. Richard, Salmon, Dennis J., Walsh, Jerry L., Abruna, Hector D., and Meyer, Thomas J. (1980) Oxidation of the ligand in nitro complexes of ruthenium(III). Inorganic Chemistry, 19 (7). pp. 1896-1903.

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Abstract

Nitro complexes of bis(bipyridyl)ruthenium(III) are unstable with respect to oxidation of the coordinated nitro ligand. For the complexes Ru(bpy),(L)NOz' (L = NH,, py (pyridine), pyr (pyrazine), CH3CN, PPh,) and Ru(bpy),(CI)N02, electrochemical oxidation to the ruthenium(II1) state results in production of the corresponding nitrosyl and nitrato complexes in a 1:l ratio. A two-electron oxidation of the nitro ligand to nitrate occurs, and the corresponding reduction is delocalized over two sites, one at the metal (Ru"' - Ru") and one at the ligand (RuNO' - Ru&O). For the chloro complex the rate of disappearance of Ru"'(bpy),(C1)NOz+ is first order in Ru(II1) and the rate constant, determined by monitoring the reaction by cyclic voltammetry, is 1.8 X sd in acetonitrile at room temperature. For the pyridyl complex, variable scan-rate cyclic voltammetry experiments show the intervention of an intermediate past the initial oxidation step. A mechanism is suggested for the oxidation of coordinated nitrite which consists of an initial rearrangement of the nitro ligand from N bound to 0 bound. The 0-bound isomer is a reactive intermediate which undergoes a bimolecular oxygen atom transfer reaction probably with the corresponding Ru"-N02 complex to give the observed products. The acid-base properties of the R~(bpy)~(py)NO~~-Ru(bpy)~(pya)cNidO-~ba's e pair and formal reduction potentials for the chloro and pyridyl complexes as two-electron-acceptor, oxide ion donor oxidants have been determined. In basic solutions, oxidation of the nitro group becomes catalytic and the nitrato complex is the sole product of the oxidation.

Item ID:	22788
Item Type:	Article (Research - C1)
ISSN:	1520-510X
Date Deposited:	29 Aug 2012 01:14
FoR Codes:	03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030207 Transition Metal Chemistry @ 100%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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