Rate (k) and equilibrium constants (K) have been measured for 17 non-degenerate hydride-transfer reactions, the donors and acceptors generally being variously substituted and elaborated pyridinium ions. Rate constants have also been measured for 6 degenerate reactions of the same type. These results have been used to test the Marcus theory of atom transfer. The Brønsted plot shows a good deal of scatter, but around K= 1.0 it has about the predicted slope (α) of 0.5. Using the measured values of k for degenerate reactions and assuming intrinsic reactivity to be constant within structural families, values of k for 12 non-degenerate reactions were calculated without introducing adjustable parameters. They reproduce 99% of the variation in the measured values, the measured values generally being larger than the calculated values. The data do not permit a test of the predicted variation of α with K.A proposed mechanism involving electron transfer followed by proton transfer followed by another electron transfer, with metastable intermediates between the steps, can be excluded. Such a mechanism would lead to values of k below those predicted by the theory.
▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. W...
One of the active areas in reaction kinetics during the post-war years has \nbeen that of electron-transfer reactions. These reactions constitute one type \nof oxidation...
A series of substituted styrenes were polymerized by controlled/"living" radical polymerization using atom transfer radical polymerization (ATRP), in order to correlate monomer ...
A mechanism is described for chemiluminescent electron-transfer reactions. It is shown that in the case of very exothermic homogeneous electron-transfer reactions, the intersect...
A simple relation, ΔF* = (λ(1 + Δ/λ)^2)/4, derived originally for weak-overlap electron transfers, is explored in a slightly modified version for reactions with considerable res...
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