Electrocatalytic oxidation by binuclear ruthenium complexes incorporating the anionic tripod ligand [([eta][sup 5]-C[sub 5]H[sub 5])Co[l brace](CH[sub 3]O)[sub 2]P[double bond]O[r brace][sub 3]][sup [minus]]
- California Inst. of Technology, Pasadena (United States)
The two-phase reaction of 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]]) in 1% H[sub 2]SO[sub 4] with RuO[sub 4] in CCl[sub 4] affords the edge-sharing octahedral dimer [(L[sub OMe])(HO)Ru[sup IV]([mu]-O)[sub 2]Ru[sup IV](OH)(L[sub OMe])] which is diprotonated by aqueous CF[sub 3]SO[sub 3]H to the corresponding salt [(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]. This dimer salt is oxidized by C[sub 6]H[sub 5]IO in CH[sub 3]CN to [(O[sub OMe])(O)Ru[sup V]([mu]-O)[sub 2]Ru[sup V](O)(L[sub OMe])] and reduced by alcohols, aldehydes, or triphenylphosphine in CH[sub 3]CN to [(L[sub OMe])(CH[sub 3]CN)Ru[sup III]([mu]-OH)[sub 2]Ru[sup III](NCCH[sub 3])(L[sub OMe])][CF[sub 3]SO[sub 3]][sub 2]. In buffered aqueous solution, the diprotonated Ru[sup IV]-Ru[sup IV] dimer reacts with formaldehyde to afford a triply bridged dimer, [(L[sub OMe])Ru[sup IV]([mu]-O)[sub 2]([mu]-HCOO)Ru[sup III](L[sub OMe])][CF[sub 3]SO[sub 3]]. The latter reaction appears to be autocatalytic via an inner-sphere mechanism. The Ru[sup III]-Ru[sup III] formate adduct is oxidized by AgCF[sub 3]SO[sub 3] to the Ru[sup IV]-Ru[sup IV] analog [(L[sub OMe])Ru[sup IV]([mu]-O)[sub 2]([mu]-HCOO)Ru[sup IV](L[sub OMe])][CF[sub 3]SO[sub 3]], which slowly reacts with aqueous formaldehyde to regenerate the Ru[sup III]-Ru[sup III] adduct and free formate. The dimeric system in aqueous solution functions as an electrocatalyst for the oxidation of formaldehyde at low anodic potentials (near 0.0 V versus SCE at pH 8.5). Both Ru[sup III]-Ru[sup III] dimers have been characterized by X-ray crystallography. 27 refs., 8 tabs., 6 figs.
- OSTI ID:
- 5845288
- Journal Information:
- Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 32:13; ISSN 0020-1669; ISSN INOCAJ
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
ALCOHOLS
ALDEHYDES
ANIONS
CATALYSTS
CHARGED PARTICLES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COBALT COMPLEXES
COHERENT SCATTERING
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTROCATALYSTS
FORMALDEHYDE
HYDROXY COMPOUNDS
IONS
MONOCLINIC LATTICES
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PHOSPHINE OXIDES
PHOSPHINES
PHOSPHORUS COMPOUNDS
RUTHENIUM COMPLEXES
SCATTERING
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
TRICLINIC LATTICES
X-RAY DIFFRACTION