Remarks on the trinuclear acetato complexes of iron(III), chromium(III) and aluminium

Abstract

The reaction between acetic anhydride and the hydrated nitrates of iron(III), chromium (III) and aluminium has been re-examined. Nitrates of unipositive acetato-hydroxo complexes are formed as intermediates whose composition is [M 3(OCOCH 3) 7OH· nH 2O]NO 3 with n varying from 0 to 4. In the final stage of the reaction, an additional acetato group replaces the nitrate ion while the hydroxo group is carried into the end product. The reaction, therefore, is not useful for the preparation of the pure tri-acetates of the formula M(OCOCH 3) 3. The experiments provide evidence for unipositive trinuclear acetato complexes of aluminium whose existence has been obscured by their relatively low stability as compared to the complexes of iron and chromium.