Dioxygen chromium oxidation

Electronic properties of intrazeolitic complexes of transition metal ions with oxygen are of Interest for elucidation of oxygen binding and its activation for oxidation reactions. In an earlier study, dioxygen and monooxygen chromium species were reported to be formed by specific interactions between the oxygen molecules and the Cr ions planted in the Type A zeolite (1). 

Coordinatively saturated metal complexes that are kinetically inert with respect to ligand substitution may undergo outer-sphere electron transfer reactions with dioxygen. Typical examples include oxidations of six-coordinate chromium(II) complexes29 (Equation 4.6) and oxidations of polyoxometallate anions.30... 

III.B.2), complexes with manganese, chromium, as well as second- and third-row transition metal ions (e.g., ruthenium) oxidation reactions with dioxygen alone or with other peroxides (e.g., ferf-butyl-peroxide) the stabilization and spectroscopic characterization of mononuclear superoxo, peroxo, and oxo complexes other catalytic processes (e.g., the iron-catalyzed aziridination), enantioselective reactions with chiral bispidine ligands and the iron oxidation chemistry continues to produce novel and exciting results. 

As mentioned above, fundamental studies of the [Cr, 02] system indicate that low-valent Cr may be able to mediate the spin inversion of dioxygen in the transformation Cr(02) - Cr02. The high-valent chromium-dioxide cation is in turn a powerful oxidant in the gas phase, capable even of activating methane [31]. However, previous evidence for the crucial spin inversion in the [Cr, 02] system remained circumstantial. We, therefore, wished to... 

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