Inverted redox catalysis: catalysis of substitution on ruthenium(II) by an extraordinarily labile ruthenium(III) metal center

Journal Article · Wed Sep 13 04:00:00 EDT 1978 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00487a061· OSTI ID:6598797

Matsubara, T; Creutz, C

The kinetics of the substitution reaction of ruthenium(II) complex, Ru(edta)(H/sub 2/O)-pKa(-CO/sub 2/H) = 2.37, pKa(-OH/sub 2/) = 7.5 were studied in buffered aqueous solutions (0.1M acetate buffer (pH 5.5), ..mu.. = 0.2M KCF/sub 3/SO/sub 3/, 25/sup 0/C) by the stopped-flow technique. The forward rate constants were large and varied greatly with the nature of the entering ligand (L,k/sub 2/(m/sup -1/s/sup -1/): CH/sub 3/CN, 30 +- 7; SCN/sup -/, (2.0 +- 0.1) x 10/sup 2/; isonicotinamide, (8.3 +- 0.6) x 10/sup 3/; pyrazine, (2.0 +- 0.1) x 10/sup 4/). The data suggest a very high degree of bond making in the transition state and provide evidence for associative character in the nucleophilic substitution on Ru(III) in Ru(edta)(H/sub 2/O)/sup -/. Variation of the substitution rates with pH suggest that Ru(edta)(H/sub 2/O)/sup -/ is the predominant reactive form over pH range 0.7 to 10. The large rates found for substitution on Ru(III)(edta)(H/sub 2/O)/sup -/ support the hypothesis that this species is responsible for the anomalies encountered in the Ru(II)(edta)(H/sub 2/O)/sup 2 -/ kinetic studies.

• Research Organization: Brookhaven National Lab., Upton
• OSTI ID: 6598797
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 100:19; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMIDES
AQUEOUS SOLUTIONS
AZINES
BONDING
CARBONIC ACID DERIVATIVES
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DISPERSIONS
ELEMENTS
FABRICATION
HETEROCYCLIC COMPOUNDS
JOINING
KINETICS
LIGANDS
MEDIUM TEMPERATURE
METALS
MIXTURES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PH VALUE
PLATINUM METALS
PYRAZINES
REACTION INTERMEDIATES
REACTION KINETICS
REDOX REACTIONS
REFRACTORY METALS
RUTHENIUM
RUTHENIUM COMPLEXES
SOLUTIONS
TEMPERATURE DEPENDENCE
THIOCYANATES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS