Oxidation by dioxygen of manganese(II) and iron(II) complexes

Fast oxidations of the iron(II)N,N-dialkylcarbamato complexes [Fe(II)(O2CNR2)(2)](n) (R = Et, n = 6, 1; R = Pr-i, 2) and [Fe(II)(8)(mu(4)-O)(2)((O2CNPr2)-Pr-i)(12)], 3, by dioxygen were carried out both in an anhydrous hydrocarbon and in the solid state affording [Fe(III)(2)(O)(O2CNR2)(4)](x), 7 and 8 for R = Et and Pr-i, respectively, and [Fe(III)(4)(O)(3) ((O2CNPr2)-Pr-i)(6)](y), 9. The stoichiometric O-2 uptake was not accompanied by oxidation of the ligand. Recovery of unchanged starting material was observed when the manganese(II) derivatives [Mn(II)(O2CNR2)(2)](n) (R = Et, n = 6, 4; R = Pr-i, 5) were treated with O-2. Nevertheless, when [Mn(II)(8)(mu(4)-O)(2)((O2CNPr2)-Pr-i)(12)], 6, prepared in situ by reaction of 5 with water (Mn/H2O molar ratio = 4), was reacted with O-2, complete oxidation occurred to a product where manganese showed an average. oxidation number III, [Mn(III)(4)(O)(3) ((O2CNPr2)-Pr-i)(6)](y), 10. The product [Mn(II)(6)Mn(III)(2)(mu(4)-O)(2)(mu(3)-O)((O2CNPr2)-Pr-i)(12)], 11, obtained by partial oxidation of 6 by 02, has been characterised by X-ray diffraction methods.