PROBING THE CHEMISTRY OF ORGANOMANGANESE COMPLEXES - A KINETIC-STUDY OF THE ROLE OF COORDINATE BONDS IN A DEMETALATION REACTION

The kinetics of demetalation of a series of aryl-substituted manganacy cles was measured to ascertain the relationship between the electronic nature of the manganacycle substitutents and the strength of the coor dinate bond between the carbonyl oxygen and the metal center. Hammett and Arrhenius analyses were performed on these complexes and the activ ation parameters for demetalation were determined. These analyses were consistent with a mechanism (Scheme 4) in which the coordinate mangan ese-oxygen bond is highly broken in the transition state for demetalat ion. Correlation of the kinetic data with the Mn-55 chemical shifts of the mariganacycles was not possible in this system.