MAGNETODYNAMIC EFFECTS ON OUTER-SPHERE ELECTRON-TRANSFER REACTIONS - A PARAMAGNETIC TRANSITION-STATE

The effect of the magnetic field on the rate of outer-sphere electron-transfer reactions has been investigated as a function of the field intensity, between 0 and 9 T, and at a given temperature. In complexes of d6metal ions, i.e., Ru(II) and Co(III), the rate constant exhibits a complex dependence on the field: a complexity associated with field-induced changes of the electronic matrix element and the activation energy. Changes in the activation energy have been investigated as a function of the temperature at a given field intensity. These measurements have shown that the magnetic susceptibility of activation has the large positive values that are expected for a strongly paramagnetic transition state. The magnetic field effects are discussed in terms of symmetry-determined selection rules for the coupling of the initial and final electronic states of the reactions. © 1990, American Chemical Society. All rights reserved.