Magnetic field effects on the reactivity of co-ordination complexes: a probe of the transition-state magnetic properties in outer-sphere electron transfers

Abstract

The effect of the magnetic field on the rate of the outer-sphere electron-transfer reaction between [Co(NH₃)₆]³⁺ and [Ru(NH₃)₆]²⁺ has been investigated under fields 0 ⩽H⩽ 9 T. An approximate functional dependence, k(H)/k(0)= 1 – 0.295H+ 0.157H²– 0.0281H³+ 0.0016H⁴+⋯ has been found for the ratio of the rate constants determined at H and 0 respectively. The results have been interpreted in terms of a transition state where the magnetic dipoles of the cobalt and ruthenium species are strongly coupled.