Electron-transfer reactions of technetium and rhenium complexes. 2. Relative self-exchange rate of the M(I)/M(II) couples [M(DMPE)3]+/2+ where M = Tc or Re and DMPE = 1,2-bis(dimethylphosphino)ethane

1988 ◽  
Vol 27 (6) ◽  
pp. 999-1003 ◽  
Author(s):  
Karen Libson ◽  
Mary Woods ◽  
James C. Sullivan ◽  
J. W. Watkins ◽  
R. C. Elder ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Transfer Reactions ◽  
Rhenium Complexes ◽  
Electron Transfer Reactions

Kinetics of electron-transfer reactions of the Co(bpyO2)32+/3+ couple in acetonitrile

1992 ◽  
Vol 70 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Donal H. Macartney ◽  
Samuel Mak
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Rate Constants ◽  
Marcus Theory ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
Cross Reactions ◽  
The Cross ◽  
Polypyridine Complexes ◽  
Kinetics Of

The kinetics of the outer-sphere electron transfer reactions of tris(1,1′-dioxo-2,2′-bipyridine)cobalt(II) and (III) with a series of nickel polyaza macrocycles, FeL3n+ and OsL32+ complexes (L is 2,2′-bipyridine or 1,10-phenanthroline, and substituted derivatives), and Rh2(O2CCH3)4(CH3CN)2+ have been investigated in acetonitrile at 25.0 °C. An application of the Marcus theory relationship to the cross-reaction rate constants yielded apparent Co(bpyO2)32+/3+ self-exchange rate constants of 102 M−1 s−1 from the nickel macrocycle cross-reactions and 10−1 M−1 s−1 from the cross-reactions with the metal polypyridine complexes. The latter cross-reactions are considered to be non-adiabatic due to a mismatch in the donor/acceptor orbital symmetries. The electron exchange rate constant is compared with the exchange rate constants for other Co(II)/Co(III) complex couples and M(bpyO2)32+/3+ couples of other first-row transition metals, and discussed in terms of inner-sphere and solvent reorganization barriers. Keywords: electron transfer, Marcus theory relationship, cobalt(II)/(III) couples, 1,1′-dioxo-2,2′-bipyridine.

Kinetics and mechanism of the oxidation of benzenediols and ascorbic acid by bis(1,4,7-triazacyciononane)nickel(III) in aqueous perchlorate media

1985 ◽  
Vol 63 (6) ◽  
pp. 1198-1203 ◽  
Author(s):  
A. McAuley ◽  
Lee Spencer ◽  
P. R. West
Keyword(s):  
Electron Transfer ◽  
Ascorbic Acid ◽  
Exchange Rate ◽  
Rate Constants ◽  
Outer Sphere ◽  
Kinetics And Mechanism ◽  
Hydrogen Ion ◽  
Transfer Reactions ◽  
Radical Ions ◽  
Electron Transfer Reactions

The reactions of the outer-sphere electron transfer reagent, Ni(9-aneN3)23+, (bis(1,4,7-triazacyclononane)nickel(III) ion) with ascorbic acid, hydroquinone, catechol, and resorcinol have been investigated. The absence of any proton related equilibria with the oxidant provides a means of ascribing the observed inverse hydrogen ion dependences to reactions of the dissociated ascorbate or quinolate ions, (HA−). The data are consistent with the rate-determining one-electron transfer reactions:[Formula: see text]followed by rapid oxidation of the radical ions formed. In the reaction with ascorbic acid, k1 ~ 0 and k2 (T = 25° C) = 5.2 × 106 M−1 s−1 (ΔH≠ = 10.1 ± 2.5 kcal mol−1, ΔS≠ = 5.7 ± 5.1 cal mol−1 K−1). For hydroquinone, catechol, and resorcinol, k1 = 2.9 × 103, 2.8 × 102, and ~0 M−1 s−1and k2 = 6.9 × 109, 4.1 × 109, and 2.8 × 108 M−1 s−1, respectively. These data have been combined with those from other similar reactions leading, by use of a Marcus correlation, to self-exchange rate constants for the HAsc−/HAsc• couple of 3.5 × 105 M−1 s−1 and for the H2Quin0/+ and H2cat0/+ systems of 5 × 107 and 2 × 107 M−1 s−1, respectively. The importance of the effect of bond-reorganisation on electron transfer is discussed.

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