Browsing by Author "Jordan, Robert B."

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    Oxidation of ferrocenes by copper(II) in aqueous acetonitrile: nitrate and chloride ion effects
    (2007) Irwin, Robert; Jordan, Robert B.
    The effect of nitrate and chloride ion on the rate of oxidation of ferrocene (Fc) and 1,1‘-dimethylferrocene (DmFc) by Cu(II) has been studied in 95% and 80% acetonitrile/water solutions. The complex formation constants for Cu(II) with the same anions in the same media have been determined by spectrophotometry. Nitrate ion mildly inhibits the reaction, while chloride ion substantially increases the rate. The results have been analyzed in terms of the Marcus theory, and it is concluded that complexation increases the rate of self-exchange between the CuII(X)n and CuI(X)n species. In the case of nitrate, the latter effect is compensated for by a less favorable overall equilibrium constant, which results in mild inhibition.
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    Reaction of copper(II) with ferrocene and 1,1 '-dimethylferrocene in aqueous acetonitrile: the copper(II/I) self-exchange rate
    (2005) Irangu, Japhet; Ferguson, Michael J.; Jordan, Robert B.
    The kinetics of the reactions of copper(II) with ferrocene (Fc) and 1,1‘-dimethylferrocene (Dmfc) have been studied at 25 °C in aqueous acetonitrile (AN) containing 50−97.5 vol % AN. With increasing % AN, the rate constant increases along with the driving-force for the reaction. The results are analyzed in terms of Marcus theory to estimate the Cu(II/I) electron self-exchange rate constant (k11) for the system. Over the solvent range studied, the calculated k11 changes from 1.1 × 10-9 to 17 × 10-9 M-1 s-1, with an average value of 5 × 10-9. In addition, the structures of the trifluoromethanesulfonate salts of [Cu(AN)4]+, [Cu(OH2)2(AN)2]2+, and [Cu(AN)4]2+ are reported. It is found that the Cu−NCCH3 bond-length difference between the Cu(I) and Cu(II) oxidation states is only ∼0.02 Å.