Characterization of Chromium(III) Acetate in Aqueous Solution

Abstract

FT-IR, ²H NMR, FAB mass spectrometry, and ion exchange chromatography were used to characterize structures in chromium acetate solutions prepared under several different conditions. Infrared and ²H NMR peaks for ionic, unidentate, bidentate, and bridging acetate groups were assigned on the basis of chemical information and appearance/disappearance correlations. FAB mass spectrometry was used to confirm the existence of the cyclic chromium trimer in solution. Ion exchange chromatography allowed separation of the complexes based on ionic charge. Replacement of acetate groups by hydroxyl groups causes ring opening and the formation of linear species. Many commercial chromium(III) acetates contain oxalate as well as acetate ligands.