NONBRIDGING LIGAND EFFECTS ON RATE OF VANADIUM(2) REDUCTION OF SOME COBALT(3) COMPLEXES

The rates of reduction of several Co(III) complexes by V(II) have been measured at 25° in a medium of unit ionic strength. The Co(III) complexes all contain a CI- in the first coordination sphere, but the other ligands are varied. This variation leads to measured second-order rate constants between 2 and about 500 M-1 sec-1. These rate constants correlate well with the previously reported data on the Fe(II) reduction of the same complexes. What the implications of these linear free energy relationships are is discussed. The mechanism of the fastest of the V(II) reductions must be outer sphere; the mechanism of the slower reactions may be outer sphere also. © 1969, American Chemical Society. All rights reserved.