Identification of inner- and outer-sphere paths in the reaction of chromium(II) with hexachloroiridate(IV), and the kinetics of the decomposition of the binuclear intermediate

1970 ◽  
pp. 232 ◽  
Author(s):  
A. G. Sykes ◽  
R. N. F. Thorneley
Keyword(s):  
Outer Sphere ◽  
Kinetics Of

Electrode kinetics of Eu3+/Eu2+ reaction by cyclic voltammetry

1982 ◽  
Vol 47 (7) ◽  
pp. 1773-1779 ◽  
Author(s):  
T. P. Radhakrishnan ◽  
A. K. Sundaram
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Outer Sphere ◽  
Electrode Reaction ◽  
Transfer Reactions ◽  
Cyclic Voltammetric ◽  
Edta Solution ◽  
Kinetics Of ◽  
Activated Complex ◽  
Good Agreement

The paper is a detailed study of the cyclic voltammetric behaviour of Eu3+ at HMDE in molar solutions of KCl, KBr, KI, KSCN and in 0.1M-EDTA solution with an indigenously built equipment. The computed values of the rate constants at various scan rates show good agreement with those reported by other electrochemical methods. In addition, the results indicate participation of a bridged activated complex in the electron-transfer step, the rate constants showing the trend SCN- > I- > Br- > Cl- usually observed for bridging order of these anions in homogeneous electron-transfer reactions. The results for Eu-EDTA system, however, indicate involvement of an outer sphere activated complex in the electrode reaction.

Complexation Kinetics of Copper(II) and Nickel(II) with Macrocycles:  Identification of an Outer-Sphere Chelate Effect

2007 ◽  
Vol 46 (10) ◽  
pp. 4002-4009 ◽  
Author(s):  
Nichola McCann ◽  
Geoffrey A. Lawrance ◽  
Yorck-Michael Neuhold ◽  
Marcel Maeder
Keyword(s):  
Outer Sphere ◽  
Chelate Effect ◽  
Kinetics Of ◽  
Complexation Kinetics

1H and 13C NMR Study of Proton Transfer in Azoles. Mechanism of Proton Transfer in Pyrazole in Solutions Containing bis-(Acetylacetonato) Nickel (II)

1976 ◽  
Vol 31 (7-8) ◽  
pp. 353-360 ◽  
Author(s):  
V. N. Babin ◽  
E. B. Zavelovidi ◽  
E. I. Fedin
Keyword(s):  
Proton Transfer ◽  
Ligand Exchange ◽  
Hyperfine Coupling ◽  
Outer Sphere ◽  
Coupling Constants ◽  
1H And 13C Nmr ◽  
Nmr Study ◽  
Nmr Techniques ◽  
Kinetics Of ◽  
C Nmr

Abstract Proton Transfer, Pyrazole, Outer-Sphere Coordination Proton transfer in pyrazole systems involving interaction with a paramagnetic transition metal complex has been studied with 1H and 13C NMR techniques. Kinetics of the ligand exchange in the pyrazole complex of bis-(acetylacetonato) nickel (II) has been investigated, and hyperfine coupling constants for the interaction of the nickel unpaired electron with the ligand nuclei in the complex have been determined. Catalytic admixtures of bis-(acetylacetonato) nickel (II) are shown to modify the mechanism of the proton transfer in pyrazole. The spectral data are discussed in terms of outer-sphere coordination and cooperative proton transfer effects.

Kinetics of N-substituted phenothiazines and N-substituted phenoxazines oxidation catalyzed by fungal laccases

2009 ◽  
Vol 4 (1) ◽  
pp. 62-67 ◽  
Author(s):  
Lidija Tetianec ◽  
Juozas Kulys
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Reorganization Energy ◽  
Outer Sphere ◽  
Initial Reaction Rate ◽  
Initial Reaction ◽  
Type I ◽  
Electron Transfer Mechanism ◽  
Recombinant Laccase ◽  
Kinetics Of

AbstractLaccase-catalyzed oxidation of N-substituted phenothiazines and N-substituted phenoxazines was investigated at pH 5.5 and 25°C. The recombinant laccase from Polyporus pinsitus (rPpL) and the laccase from Myceliophthora thermophila (rMtL) were used. The dependence of initial reaction rate on substrate concentration was analyzed by applying the laccase action scheme in which the laccase native intermediate (NI) reacts with a substrate forming reduced enzyme. The reduced laccase produces peroxide intermediate (PI) which in turn decays to the NI. The calculated constant (kox) values of the PI formation are (6.1±3.1)×105 M−1s−1 for rPpL and (2.5±0.9)×104 M−1s−1 for rMtL. The bimolecular constants of the reaction of the native intermediate with electron donor (kred) vary in the interval from 2.2×105 to 2.1×107 M−1s−1 for rPpL and from 1.3×102 to 1.8×105 M-1s−1 for rMtL. The larger reactivity of rPpL in comparison to rMtL is associated with the higher redox potential of type I Cu of rPpL. The variation of kred values for both laccases correlates with the change of the redox potential of substrates. Following outer sphere (Marcus) electron transfer mechanism the calculated activationless electron transfer rate and the apparent reorganization energy are 5.0×107 M−1s−1 and 0.29 eV, respectively.

Reduction of hexaammineruthenium(III) ions by a series of tris(polypyridyl)chromium(II) ions – Revisiting the Cr(NN)33+/2+ self-exchange rate

2001 ◽  
Vol 79 (7) ◽  
pp. 1124-1127 ◽  
Author(s):  
K Omar Zahir
Keyword(s):  
Exchange Rate ◽  
Excited States ◽  
Rate Constants ◽  
Driving Force ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Outer Sphere ◽  
Laser Flash ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of the outer-sphere oxidation of Cr(NN)32+ ions (NN = 2,2'-bipyridine, 1,10-phenanthroline, and their substituted analogs) by hexaammineruthenium(III) was studied using laser flash photolysis. The Cr(NN)32+ ions were generated via the reductive quenching of the *Cr(NN)33+ excited states by oxalate ions or by H2edta2–. The second-order rate constants were found to vary with the driving force of the reaction. The rate constants increase from (7.1 ± 0.5) × 106 M–1 s–1 for Cr(5-Clphen)32+ to (2.6 ± 0.2) × 108 M–1 s–1 for Cr(4,7-Me2phen)32+. The self-exchange rate constant for the couple (Cr(NN)33+/2+) was calculated by applying Marcus cross relation to present and other known reactions of Cr(NN)3n+ ions, where n = 3 or 2 with various reactants and is estimated to be (6 ± 4) × 107 M–1 s–1.Key words: tris(polypyridyl)chromium(II)/(III) self-exchange rate, hexaammineruthenium(III), oxidation of Cr(NN)32+.

The Kinetic Activation Volumes for the Binding of Iodide to Cobalamin (Vitamin B12) Studied on a High Pressure Laser Temperature Jump Apparatus

1974 ◽  
Vol 52 (6) ◽  
pp. 910-914 ◽  
Author(s):  
Brian B. Hasinoff
Keyword(s):  
High Pressure ◽  
Metal Ion ◽  
Temperature Jump ◽  
Outer Sphere ◽  
Dissociation Rate ◽  
Vitamin B ◽  
Laser Temperature Jump ◽  
Dissociation Rate Constants ◽  
Kinetics Of ◽  
Activated Complex

The relaxation kinetics of the reaction of iodide with cobalamin (vitamin B12) were studied on a high pressure laser temperature jump apparatus in aqueous solution at 25° and ionic strength 0.2 M. Analysis of the pressure dependence of the formation and dissociation rate constants gave their respective volumes of activation to be: ΔVf* = 5.50 ± 0.8 cm3 mol−1 and ΔVd* = 11.5 ± 1.6 cm3 mol−1 The positive activation volume for formation of the complex, ΔVf*, after appropriate correction for the volume change due to formation of an outer sphere complex, is consistent with a dissociative type mechanism in which the metal ion – water bond is stretched in the activated complex.

The Oxidation of Dithiocarbamate Anion by Substitution Inert Metal Complexes

1989 ◽  
Vol 42 (7) ◽  
pp. 1085 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Metal Complexes ◽  
Radical Anion ◽  
Outer Sphere ◽  
Aqueous Acetone ◽  
Kinetics Of Oxidation ◽  
Rate Determining Step ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of oxidation of dithiocarbamate anions to thiuram disulfides in aqueous acetone by {Fe(CN)6}3- and 11 other substitution inert metal complexes have been investigated. Outer-sphere electron transfer, resulting in the formation of dithiocarbamate thio radicals, is the rate determining step. A Marcus cross reaction treatment allows an estimate for the redox potential for the dithiocarbamate radical/anion couple. For diethyldithiocarbamate, E �(edtc/edtc-) = 425 � 33 mV v.s.c.e. and the outer-sphere electron self-exchange rate constant is log kex = 7.0 � 0.3. A comparison with thiophenolate oxidation is also given.

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