- Syntheses, structural analyses and redox kinetics of four-coordinate [CuL2]2+ and five-coordinate [CuL2(solvent)] 2+ complexes (L = 6,6′-dimethyl-2,2′-bipyridineor2,9- dimethyl-l,10-phenanthroline): Completely gated reduction reaction of [Cu(dmp)2]2+ in nitromethanet
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[Cu(2,9-dimethyl-1,10-phenanthroline)2]2+ and [Cu(6,6′-bipyridine)2]2+/+ complexes with no coordinated solvent molecule were synthesized and crystal structures were analyzed. Electrochemical measurement were carried out by using a BAS 100B/W electrochemical analyzer. The coordination geometry around the Cu(I) center was in the D2d symmetry while a D2 structure was observed for the four-coordinate Cu(II) complexes. The study revealed that the D2 structure of the Cu(I) complex retained in nitromethane, although a five-coordinate Thp species, was readily formed upon dissolution of the solid in acetonitrile.
- Itoh, Sumitaka,Kishikawa, Nobuyuki,Suzuki, Takayoshi,Takagi, Hideo D.
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p. 1066 - 1078
(2007/10/03)
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- Estimation of One-Electron Oxidation Potentials of Some Donors Based on Data of Rate Constants for Their Interactions with Chlorine Dioxide
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Reduction of ClO2. by various one- and two-electron donors is studied.The electron transfer rate constants (k) for the donors were measured directly, and their one-electron redox potential (φ) were either obtained by direct thermodynamic measurements or reliably established by various estimations and calculations with convergent results.An approximate linear dependence was found: log k = -12φ + 14.3, where k is in mol-1 s-1 and φ is in V.This dependence and the results of kinetic measurements are used to obtain the following one-electron redox potentials: φ(Sn3+/Sn2+) = 0.97 V, φ(PhO./PhO-) = 0.58 - 0.65 V, φ(SO3.-/SO32-) = 0.66 V, and φ(HCOO./HCOO-) = 1.45 V.
- Kozlov, Yu. N.
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p. 218 - 220
(2007/10/02)
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- Electron-transfer reactions of copper(I) and (2,9-dimethyl-1,10-phenanthroline)copper(II) with some ammine complexes of ruthenium (III) and -(II)
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Second-order rate constants have been determined for the oxidation of Cu(aq)+ by various Ru(III) complexes in perchlorate solutions at 25°C and 1.0 M ionic strength. Values of the rate constants (M-1 s-1): Ru(NH3)5py3+, 46.6; Ru(NH3)5isn3+, 540; Ru(NH3)4bpy3+, 3.8 × 103; Ru(NH3)4(isn)23+, 4.4 × 104. These data and previously measured values of Cu(aq)+-Ru(III) reactions follow a linear free energy relationship between log k2 and E°, the reduction potential of the Ru(III) complexes. Rate constants for the one-electron oxidations of Ru(NH3)5py2+, Ru(NH3)5isn2+, and Ru(NH3)4bpy2+ by the (2,9-dimethyl-1,10-phenanthroline)copper(II) ion, Cu(dmp)22+, were found to be 5.50 × 105, 4.55 × 105, and 3.86 × 105 M-1 s-1, respectively, in an MES-buffered 0.10 M LiCF3CO2 medium between pH 5.1 and 7.0. Activation enthalpies, ΔH? = 21.6, 22.6, and 23.7 kJ mol-1, and activation entropies, ΔS? = -64, -59, and -58 J mol-1 K-1, were measured for the same reactions. Application of the Marcus relations leads to estimated exchange rate constants of 2 × 10-4 and 4 × 104 M-1 s-1 for the Cu(aq)+/Cu(aq)2+ and Cu(dmp)2+/Cu(dmp)22+ couples. The exchange rates are discussed in terms of the inner-shell reorganizations at the copper centers.
- Davies, Keith M.
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p. 615 - 619
(2008/10/08)
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