Anion-Catalyzed Heterolysis of Chromium-Carbon σ Bonds. Effect of Different Anions, Temperature, and Pressure

The anion-catalyzed heterolysis reaction of (H₂O)₅CrC(CH₃)₂OH²⁺ was studied as a function of anion concentration, temperature, and pressure for a series of 10 different organic and inorganic oxy anions, for which the pK_a values range between 0 and 7. The reported rate data indicate that the catalytic effect increases with basicity of the anion. The volumes of activation for the catalyzed heterolysis reactions are all significantly positive and support the operation of a dissociatively activated heterolysis mechanism. The results are discussed in reference to related data reported in the literature.