One-electron reduction of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of cobalt(III) in aqueous solution. [Pulsed irradiaion]

Journal Article · Thu Feb 22 04:00:00 EST 1979 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100467a003· OSTI ID:6168877

Simic, M G; Hoffman, M Z; Cheney, R P; Mulazzani, Q G

The reaction of Co(2,2'-bipyridine)/sub 3//sup 3 +/ with radiation-generated reducing radicals (e/sub aq//sup -/, CO/sub 2//sup -/, (CH/sub 3/)/sub 2/COH, and CH/sub 2/OH) in aqueous solution quantitatively and rapidly (k = 10/sup 8/ - 10/sup 10/ M/sup -1/ s/sup -1/) yields high-spin (t/sub 2g//sup 5/ e/sub g//sup 2/) Co(bpy)/sub 3//sup 2 +/ (lambda/sub max/ 300 nm, epsilon/sub max/ 4.2 x 10/sup 4/ M/sup -1/ cm/sup -1/) which slowly (k = 3.4 s/sup -1/ at pH 0.5-10.5; 8.0 s/sup -1/ at pH 0.3) equilibrates with the loss of bpy; Co(bpy)/sub 3//sup 2 +/ does not transfer an electron to O/sub 2/ or p-benzoquinone. Equilibrium mixtures of Co(bpy)/sub n//sup 2 +/ react with e/sub aq//sup -/ (k > 10/sup 10/ M/sup -1/ s/sup -1/) to produce Co(bpy)/sub n//sup +/ (lambda/sub max/ 620 nm, epsilon/sub max/ 5.1 x 10/sup 3/ M/sup -1/ cm/sup -1/). Reduction of Co(phen)/sub 3//sup 3 +/ yields Co(phen)/sub 3//sup 2 +/ (lambda/sub max/ 270 nm, epsilon/sub max 5.6 x 10/sup 4/ M/sup -1/ cm/sup -1/); conversion to the equilibrium mixture (Co(phen)/sub n//sup 2 +/) occurs in a time frame (>1 s) too long to be detected by pulse radiolysis. The relationship of these results to those of the Waltz and Pearson and Baxendale and Fiti is discussed. 38 references, 4 figures.

• Research Organization: Army Natick Research and Development Command, MA
• OSTI ID: 6168877
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:4; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
ALCOHOLS
AQUEOUS SOLUTIONS
BUTANOLS
CARBON COMPOUNDS
CARBONATES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMISTRY
COBALT COMPLEXES
COMPARATIVE EVALUATIONS
COMPLEXES
DATA
DATA FORMS
DECOMPOSITION
DISPERSIONS
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IRRADIATION
ISOLATED VALUES
KINETICS
LEPTONS
METHANOL
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
PHENANTHROLINES
PROPANOLS
PULSED IRRADIATION
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION INTERMEDIATES
REACTION KINETICS
REDUCTION
SOLUTIONS
SOLVATED ELECTRONS
SPECTRA
SPECTRAL SHIFT
TIME DEPENDENCE
TRANSITION ELEMENT COMPLEXES
YIELDS