Kinetics of the oxidation of metal complexes by manganese(III) aquo ions in acidic perchlorate media: the Mn(H/sub 2/O)/sub 6//sup 2 +/-Mn(H/sub 2/O)/sub 6//sup 3 +/ electron-exchange rate constant

Journal Article · Wed Oct 09 00:00:00 EDT 1985 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00215a022· OSTI ID:5890641

Macartney, D H; Sutin, N

The kinetics of the reduction of manganese(III) aquo ions by a series of ML/sub 32//sup +/ complexes (M = Os, Fe, Ru and L is 2,2'-bipyridine and 1,10-phenanthroline or a substituted derivative), by Fe(H/sub 2/O)/sub 6//sup 2 +/ ions, and by Ni(H/sub 2/oxime)/sup 2 +/, Ni((14)aneN/sub 4/)/sup 2 +/, and Ni-(Me/sub 6/(14)4, 11-dieneN/sub 4/)/sup 2 +/ were investigated in acidic perchlorate media at 25.0 /sup 0/C. The second-order rate constants are given by ((k/sub 1/ + K/sub 2/K/sub 1h/(H/sup +/), where k/sub 1/ and K/sub 2/ are rate constants for the Mn/sup 3 +/ and MnOH/sup 2 +/ pathways and K/sub 1h/ is the hydrolysis constant of Mn(H/sub 2/O)/sub 6//sup 3 +/ (K/sub 1h/ = 1.02 +/- 0.14 M, ..mu.. = 2.0 M). The presence of a significant MnOH/sup 2 +/ pathway for the Ni(II) complexes and for Fe(H/sub 2/O)/sub 6//sup 2 +/ is interpreted in terms of an inner-sphere mechanism. An electron-exchange rate constant of 1 x10/sup -9/ M/sup -1/s/sup -1/ for the Mn(H/sup 2/O)/sub 6//sup 2 +///sup 3 +/ couple was estimated from the ML/sub 3//sup 2 +//Mn/sup 3 +/ cross-reaction data by using a modified Marcus relationship. This value is lower than the exchange rate constant of 10/sup -4+/-1/ M /sup -1/ s/sup -1/ calculated by using a semiclassical outer-sphere model and is also lower than the value of 4 x 10/sup -3/ M/sup -1/ s/sup -1/ calculated from the oxidation of Fe(H/sub 2/O)/sub 6//sup 2 +/ by Mn(H/sub 2/O)/sub 6//sup 3 +/. The kinetics of the oxidation of Mn(H/sub 2/O)/sub 6//sup 2 +/ by Co(H/sub 2/O)/sub 6//sup 3 +/ were also studied, and the redox reactions of Mn(H/sub 2/O)/sub 6//sup 3 +/ and Co(H/sub 2/O)/sub 6//sup 3 +/ are compared. Various mechanisms for the reactions of these strong oxidants are considered. 69 references, 1 figure, 2 tables.

• Research Organization: Brookhaven National Lab., Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5890641
• Journal Information: Inorg. Chem.; (United States), Vol. 24:21
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BIPYRIDINES
CHEMICAL REACTION KINETICS
REDOX REACTIONS
COBALT COMPLEXES
HYDRATES
OXIDATION
IRON COMPLEXES
MANGANESE
REDUCTION
MANGANESE COMPLEXES
OSMIUM COMPLEXES
OXIMES
PHENANTHROLINES
RUTHENIUM COMPLEXES
AQUEOUS SOLUTIONS
CHELATES
ELECTRON EXCHANGE
ENERGY LEVELS
EXPERIMENTAL DATA
MATHEMATICAL MODELS
MEDIUM TEMPERATURE
PERCHLORATES
PH VALUE
AMINES
AROMATICS
AZAARENES
AZINES
CHEMICAL REACTIONS
CHLORINE COMPOUNDS
COMPLEXES
DATA
DISPERSIONS
ELECTRON TRANSFER
ELEMENTS
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
KINETICS
METALS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PYRIDINES
REACTION KINETICS
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties