Electron self-exchange rate constant

Fig. 5. Plot of apparent electron self exchange rate constants kf P, derived from polymer De values for films containing the indicated metals, mixed valent states, and ligands, all in acetonitrile, using Equation 2, vs. literature heterogeneous electron transfer rate constants k° for the corresponding monomers in nitrile solvents. See Ref. 6 for details. (Reproduced from Ref. 6. Copyright 1987 American Chemical Society.)...

The electron self-exchange rate constants evaluated by the Marcus expressions (using cross-reaction data) and those determined experimentally differ in the following cases. Give possible reasons for these differences. 

The electron self-exchange rate constants (At) have been assessed for the following couples at 25 °C and x = 0.1 M ... 

Electron Self-Exchange Rate Constants kese (298K) for Blue Copper Proteins Retrieved from NMR Spectra... 

Since the metal ion is involved only for the acceptor part, the dependence of A-a on [M" ] should be responsible for the change in X.da with M"" concentration. The electron self-exchange between Fc NQ and the Fc—NQ /M" complex occurs via formation of the Fc NQ/M" complex as shown in Scheme 20. According to Scheme 20, the electron self- exchange rate constant (A ex) is given by Eq. 20, where Z is the frequency factor for the intermolecular ET reaction, (A,a )... 

An attempt was made to obtain the electron self-exchange rate constant for the [Fe(CN)2-(phen)2]" couple by an electrochemical method. Real space Laplace analysis was used for the chronoamperometric response of 7.05 x 10 4 M (M = mol dm 3) solutions of the iron(III) complex with 0.1 M tetra(/t-butyl)ammonium perchlorate as supporting electrolyte. A glassy carbon working electrode with 3 mm diameter was used for the measurements. The Butler-Volmer plot gave an excellent straight line, and the electrochemical self-exchange rate constant was obained to be 1.2 X lO cm s l from the In k value at the zero over-potential. From the... 

Electron self- exchange rate constants for macrobicychc cobalt complexes. 

The rate constants, 12, of redox reactions proceeding via the outer-sphere mechanism, for example, reaction (50) (105), depend, according to the Marcus theory (85-87) (Eqs. 54 and 55), on the equilibrium constant of the cross-reaction, iiLi2, and on the electron self-exchange rate constants, and 22> of the redox couples. 

Several electron self-exchange rate constants of the Cu(II/I)aq couple, reaction (56), were derived applying the Marcus crossrelation (Table III). 

The electron self-exchange rate constants of proteins are considerably larger than those of the inorganic copper complexes (Tables IV and V) (11,25,106,111). This is attributed to the large changes in the coordination sphere structures of the Cu(II) and Cu(I) inorganic complexes in comparison to the relative rigid active sites of the proteins. 

Electron Self-exchange Rate Constants of Blue Copper Proteins... 

Electron Self-exchange Rates Constants for [CuII/DL] ... 

The electron self-exchange rate constant for the [Cr(CNdipp)6] couple (CNdipp = 2,6-diisopropylphenyl isocyanide) in CD2CI2 has been measured between -89 and +22 °C using H NMR line-broadening techniques, with an extrapolated value of 1.8 x 10 M s determined for 25 The kinetics of the outer-sphere oxidations of tris(polypyridine)chromium(II) complexes by a series of tris(chelate)cobalt(III) species have been studied in aqueous solution. " The cross-reaction rate constants obey the Marcus relationship, with the exception of [Co(bpy)3] " and [Co(phen)3] ", for which mild nonadiabaticity (/[Pg.18]

The electron self-exchange rate constants for several Fe(II)/Fe(III) porphyrin couples have been measured by H NMR line-broadening techniques in 5 1 acetone/water at -20 The relative rate constants for the [Fe(P)(l-MeIm)2] couples, P = octaethylporphyrin chlorin < isobacteriochlorin, have been attributed to differences in outer-sphere reorganization, related to the steric bulk. The rate-determining step in the metallopophyrin-catalyzed reductions of dioxygen by substituted ferrocenes is the electron transfer between the ferrocene and the metalloporphyrin (M = Fe, Co, and The Marcus relationship provides a... 

The rate constants for the cross-reactions of Cu(I) tetraaza macrocycles with a series of outer-sphere oxidants have been used to determine the electron self-exchange rate constants of several Cu(I)/Cu(II) couples [CuCMe CMJdieneNJ]-"/"-" (fcn = 23 s ), [Cu(Me4[14]-l,3,8,10-... 

The electron self-exchange rates for the [l,7-bis(5-methylimidazol-4-yl)-2,6-dithiaheptane]copper(I)/(II) couple in DMSO have been determined by H NMR line broadening as a function of temperature, with fcn = 4 x 10 M s" at 28 An electron self-exchange rate constant of 1.3 x 10" M s has been measured for the [Cu((imidH)2DAP)] /" couple (imidH)2DAP = 2,6-bis[l-((2-... 

Proton NMR line-broadening techniques have been used to measure the electron self-exchange rate constants for the bis(t-butyl[8]annulene)ytter-bate(II)/(III) couple in THF (19.3 °C) in the presence (kn = 1 x 10 s" ) and... 

Electron self-exchange rate constants of the native and [Fe4Se4] reconstituted HIPIPred/ox couples have been determined to be 1.7 x 10" and 7 x respectively, from NMR Tj measurements. Diethyl pyrocarbonate modification of His-42 of HIPIPred and HIPIPox has indicated that the pH rate dependences of the redox reactions of HIPIPred/ox with the [Co(phen)3] / and [Fe(CN)6] couples are related to the proton equilibrium of His-42 (pK = 7.0), and the resulting changes in the redox potential. ... 

Table 1. Experimental values of electron self-exchange rate constants for a selection of inorganic complexes and metalloproteins...

Note that the lateral electron-hopping diffusion coeflScient can be related to the bimolecular electron self-exchange rate constant via the expression... 

The kinetics of several electron transfer reactions of the molybdenum cuboidal system [Mo4S4(edta)2]" ( = 2, 3, 4) with cross-reactants such as [Co(edta)]-, [Fe(edta)]-, [Co(dipic)2] , [Fe(H20)e], and [Pta ] -, have been investigated. The electron self-exchange rate constants determined for the [Mo4S4(edta)2] and [Mo4S4(edta)2] couples, by an application of the Marcus relationship, are 1.5 x 10 and 7.7 x 10 M s , respectively. The rate constants for the outer-sphere oxidation of two dimeric complexes, [MoW 0)2(p-edta-AT,lV )]2- and [W2(0)2(p-0)(p-S)(p-edta-Ar,iV )] -, by [IrCl ] in addic aqueous solution have been measured. While the oxidation of the former complex shows a simple second-order rate law, the kinetics of the oxidation of the latter complex exhibited a rate retardation in the presence of the [IrCl6] complex. 

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