Properties and reactivities of pentadentate ethylenediaminetetraacetate complexes of ruthenium(III) and -(II)
Journal Article
·
· Inorg. Chem.; (United States)
The reaction of the pentadentate edta complex of ruthenium(III) with various entering ligands L has been studied as a function of pH, temperature, and L at 0.2 M ionic strength in aqueous solution. Over the pH range 0.8 to 8.5, the species Ru/sup III/(edta)H/sub 2/O/sup -/ is the sole form reactive in the substitution processes. Both forward (k/sub 1/) and reverse (k/sub -1/) rate constants Ru(edta)H/sub 2/O/sup -/ + L in equilibrium (k/sub 1/,k/sub -1/) Ru(edta)L/sup -/ + H/sub 2/O have been determined, as well as activation parameters for the complexation (k/sub 1/) process (L, k/sub 1/ in M/sup -1/s/sup -1/ (25/sup 0/C), k/sub -1/ in s/sup -1/ (25/sup 0/C), ..delta..H/sub 1//sup +/ in kcal mol/sup -1/, ..delta..S/sub 1//sup +/ in cal deg/sup -1/ mol/sup -1/): acetonitrile, 30 +- 7, 3.2 +- 0.2, 8.3 +- 0.5, -24 +- 4; thiocyanate, 270 +- 20, 0.5 +- 0.1, 8.9 +- 0.5, -18 +- 3; pyridine, 6300 +- 500, 0.061 +- 0.002; isonicotinamide, 8300 +- 600, 0.7 +- 0.2, 6.6 +- 0.5, -19 +- 3; pyrazine, 20,000 +- 1000, 2.0 +- 0.5, 5.7 +- 0.5, -20 +- 3. Forward rate constants for the analogous substitution reaction for Ru/sup II/(edta) H/sub 2/O/sup 2 -/ (25/sup 0/C, 0.2 M ionic strength) are as follows: thiocyanate, 2.7 +- 0.2 M/sup -1/s/sup -1/; acetonitrile, 13 +- 1 M/sup -1/s/sup -1/; isonicotinamide, 30 +- 15 M/sup -1/s/sup -1/. The substitution reactions of Ru/sup III/(edta)H/sub 2/O/sup -/ proceed by an associative mechanism, while those of Ru/sup II/(edta)H/sub 2/O/sup 2/- appear to be dissociative in nature. Spectra and reduction potentials for the Ru(edta)L/sup -/2-/ complexes are reported. 4 figures, 11 tables.
- Research Organization:
- Brookhaven National Lab., Upton, NY
- OSTI ID:
- 5939126
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 18:7; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
AZINES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CHELATING AGENTS
COMPLEXES
EDTA
HETEROCYCLIC COMPOUNDS
INFRARED SPECTRA
LIGANDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
PYRAZINES
PYRIDINES
QUATERNARY COMPOUNDS
RUTHENIUM COMPLEXES
SPECTRA
THIOCYANATES
TRANSITION ELEMENT COMPLEXES
400201* -- Chemical & Physicochemical Properties
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
AZINES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CHELATING AGENTS
COMPLEXES
EDTA
HETEROCYCLIC COMPOUNDS
INFRARED SPECTRA
LIGANDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
PYRAZINES
PYRIDINES
QUATERNARY COMPOUNDS
RUTHENIUM COMPLEXES
SPECTRA
THIOCYANATES
TRANSITION ELEMENT COMPLEXES