The electrocatalytic and stoichiometric oxidation chemistry of binuclear ruthenium complexes incorporating the anionic tripod ligand (([eta][sup 5]-C[sub 5]H[sub 5])Co[P(OCH[sub 3])[sub 2] (=O)][sub 3])[sup [minus]]
The anionic tripod ligand NaL[sub OMe] L[sub OMe][sup [minus]] = [([eta][sup 5]-C[sub 5]H[sub 5])CO[l brace]P(O)(OCH[sub 3])[sub 2][r brace][sub 3]][sup [minus]] reacts with RuO[sub 4] in a biphasic reaction mixture of 1% H[sub 2]SO[sub 4] and CCl[sub 4] to afford [(L[sub OMe]) (HO)Ru[sup IV]-([mu]-O)[sub 2]Ru[sup IV] (OH) (L[sub OMe])] (1), which is treated with aqueous CF[sub 3]SO[sub 3]H to generate [(L[sub OMe)(H[sub 2]O)Ru[sup IV] ([mu]-O)[sub 2]Ru[sup IV](OH[sub 2])(L[sub OMe])][CF[sub 3]SO[sub 3]][sub 2] ([H[sub 2]1][CF[sub 3]SO[sub 3]][sub 2]). Addition of iodosobenzene to an acetonitrile solution of this salt yields [L[sub OMe](O)Ru[sup V](mu]-O)[sub 2]Ru[sup V]-(O)(L[sub OMe])] (2). The dimer 1 can be reduced chemically or electrochemically to the Ru[sup III]-Ru[sup III] dimers [(L[sub OMe])(H[sub 2]O)Ru[sup III]([mu]-OH)[sub 2]Ru[sup III](OH[sub 2])(L[sub OMe])][sup 2+] and [(L[sub OMe])Ru[sup III]([mu]-OH)[sub 2]([mu]-OH[sub 2])-RU[sub III](L[sub OMe])][sup 2+] which interconvert in aqueous media. Two electron processes dominate both the bulk chemistry and the electrochemisty of 1. Among these processes are the quasi-reversible RU[sup IV]-Ru[sup IV]/Ru[sup III]-Ru[sup III] and Ru[sup III]-Ru[sup III]/Ru[sup III]/Ru[sup II]-Ru[sup II] reductions and a largely irreversible Ru[sup V]-Ru[sup V]/Ru[sup IV]-Ru[sup IV] oxidation. The dioxo dimer 2 oxidizes alcohols and aldehydes in organic media to afford 1 and the corresponding aldehydes and acids. Analogously, the Ru[sup V]-Ru[sup V]/Ru[sup IV]-Ru[sup IV] redox wave mediates the electrooxidation of alcholos and aldehydes in aqueous buffer. In this system, substrates can be oxidized completely to CO[sub 2]. The kinetic behavior of these oxidations was examined by UV-vis and chronoamperometry, respectively, and the chemistry is typical of meat-oxo complexes, indicating that electronic coupling between two metal centers does not dramatically affect the metal-oxo chemistry.
- Research Organization:
- California Inst. of Tech., Pasadena, CA (United States)
- OSTI ID:
- 7107403
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
ALDEHYDES
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTIONS
COMPLEXES
DIRECT ENERGY CONVERTERS
ELECTROCATALYSTS
ELECTROCHEMICAL CELLS
FORMALDEHYDE
FORMALDEHYDE FUEL CELLS
FUEL CELLS
HYDROXY COMPOUNDS
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDATION
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TRANSITION ELEMENT COMPLEXES