MAGNETIC-FIELD EFFECTS IN RATES OF REACTIONS BETWEEN RADICALS AND TRANSITION-METAL COORDINATION-COMPLEXES OF CO(II) AND MN(II) - PROBES FOR SPIN POLARIZATION

The effect of magnetic fields on the rates of reactions of Cl-2-, Br-2-, and CO3H with Co(II) and Mn(II) complexes was investigated as a function of the field intensity between 0 and 7 T. The Delta g mechanism and suppression of HFC-induced transitions in radical-ion pairs account for effects observed at less than 0.3 T on reactions with high-spin Co(II) complexes. In the reaction between Co(Me(6)-[14]dieneN(4))(2+) and Cl-2-, MFE on the rate are mostly related to the suppression of HFC-induced transitions in the radical-ion pairs. In a number of these processes the reaction rate constant increases with field and the sense of MFE in reactions of the CO3H radical appears inverted with respect to reactions of Cl-2- and Br-2-. A mechanism that accounts for such differences is discussed.