Electron transfer and alkyl transfer with cobaloximes in aqueous solutions. Kinetic studies by pulse radiolysis

Journal Article · Thu Aug 18 04:00:00 EDT 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100084a018· OSTI ID:7015214

Kumar, M; Natarajan, E; Neta, P ^[1]

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1. National Inst. of Standards and Technology, Gaithersburg, MD (United States)

Bis(dimethylglyoximato)cobalt(III) complexes and their alkyl derivatives were reduced by solvated electrons and by various radicals in solution. Cl(py)(dmgH)[sub 2]Co[sup III] ([lambda][sub max] 220, 244 nm) was reduced to the Co[sup II] state ([lambda][sub max] 460 nm) and then to the Co[sup 1] state ([lambda][sub max] [approximately] 540, [approximately] 630 nm). Pulse radiolysis experiments indicated that upon reduction to the Co[sup II] state, the complex loses its Cl[sup [minus]] and pyridine axial ligands within [le]0.5 [mu]s and upon further reduction to the Co[sup I] state, the complex takes up pyridine with a rate constant of 4.6 x 10[sup 7] L mol[sup [minus]1] s[sup [minus]1]. (dmgH)[sub 2]-Co[sup II] reacts with alkyl radicals (R) to form a Co-C bond. R(py)(dmgH)[sub 2]CO[sup III] (R = CH[sub 3], C[sub 6]H[sub 5]CH[sub 2], 4-carboxybenzyl) react rapidly with e[sub au]-to give transient reduced species with [lambda][sub max] near 700 nm, ascribed to R(dmgH)[sub 2]Co[sup II]. These species disappear by reaction with the starting material, R(py)(dmgH)[sub 2]Co[sup III] ([kappa] = 3.1 x 10[sup 7] for R = CH[sub 3] and 2.2 x 10[sup 8] L mol[sup [minus]1] s[sup [minus]1] for R = benzyl at pH 7) to result in the formation of dialkylcobalt complexes, whose absorption is slightly red-shifted and more intense as compared with that of the alkylcobalt complex. 37 refs., 6 figs.

• OSTI ID: 7015214
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:33; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400600* -- Radiation Chemistry
AQUEOUS SOLUTIONS
CHEMICAL BONDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COBALT COMPLEXES
COMPLEXES
DECOMPOSITION
DERIVATIZATION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
GAMMA RADIATION
IONIZING RADIATIONS
KINETICS
LEPTONS
LIGANDS
MIXTURES
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
REACTION KINETICS
REDUCTION
SOLUTIONS
SOLVATED ELECTRONS
TRANSITION ELEMENT COMPLEXES