Mechanistic implications of the active species involved in the oxidation of hydrocarbons by iron complexes of pyrazine-2-carboxylic acid.

The reactivity towards H(2)O(2) of the complexes [Fe(pca)(2)(py)(2)].py (1) and Na(2){[Fe(pca(3))](2)O}.2H(2)O.CH(3)CN (2) (where pca(-) is pyrazine-2-carboxylate) and their catalytic activity in the oxidation of hydrocarbons is reported. Addition of H(2)O(2) to 1 results in the formation of a dinuclear Fe(III)-(mu-O)-Fe(III) species characterized spectroscopically and by cyclic voltammetry. By contrast, treatment of 2 with H(2)O(2) results in the formation of mononuclear iron(II) complexes, [Fe(pca)(2)(solvent)(2)]. The experimental results indicate that the catalytic activity of the starting complexes 1 and 2 is strongly dependent on the species formed in solution.