Since the discovery that chromium is required for normal carbohydrate and
lipid metabolism in mammals and the biologically active form of chromium appears
to be the tetranuclear chromium(III) complex of oligopeptide low-molecularweight
chromium-binding substance (LMWCr), also known as chromodulin,
the chromium-carboxylate assemblies have attracted considerable attention.
Substantial efforts have been directed toward identification of functional model
for chromodulin. Such biomimetic complexes should be soluble and stable in
water solution.
In our attempts to generate new Cr(III)-containing compounds, two watersoluble
heterotrinuclear Cr-Fe propionates with 2-methylimidazole (2-MeIm),
namely [Cr2FeO(O2CC2H5)6(2-MeIm)3]NO3 (1) and [CrFe2O(O2CC2H5)6(2-
MeIm)3]NO3 (2) have been obtained from the reaction of precursor [Cr2FeO(O2
CC2H5)6(H2O)3]NO3 or [CrFe2O(O2CC2H5)6(H2O)3]NO3, respectively, with 2-MeIm
in CHCl3-acetone solution. Complexes 1 and 2 have been characterized by
elemental analysis, IR and EPR spectroscopy, mass-spectrometry and X-ray
investigations. Both compounds possess the symmetric basic carboxylate-type
structure comprised of a planar triangle Cr2Fe (1) or CrFe2 (2) with a central
μ3-oxygen. Each edge of the M3O core is bridged by two C2H5CCO2
– ligands,
the three axial positions are occupied by 2-MeIm molecules. The study of the
biological activity of these compounds is under way.
Acknowledgement. This work was supported by the U.S. Civilian Research
and Development Foundation (CRDF) (CGP Grant No. MC1-2522-CS-03)