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]]

Journal Article · Wed Jun 23 00:00:00 EDT 1993 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00065a012· OSTI ID:5845288

Kelson, E P; Henling, L M; Schaefer, W P; Labinger, J A; Bercaw, J E ^[1]

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1. 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), Vol. 32:13; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
30 DIRECT ENERGY CONVERSION
COBALT COMPLEXES
CHEMICAL PREPARATION
FORMALDEHYDE
OXIDATION
RUTHENIUM COMPLEXES
ALCOHOLS
ALDEHYDES
ANIONS
CRYSTAL STRUCTURE
ELECTROCATALYSTS
MONOCLINIC LATTICES
PHOSPHINE OXIDES
PHOSPHINES
TRICLINIC LATTICES
X-RAY DIFFRACTION
CATALYSTS
CHARGED PARTICLES
CHEMICAL REACTIONS
COHERENT SCATTERING
COMPLEXES
CRYSTAL LATTICES
DIFFRACTION
HYDROXY COMPOUNDS
IONS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
SCATTERING
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400400 - Electrochemistry
300505 - Fuel Cells- Electrochemistry
Mass Transfer & Thermodynamics