Complexation of amino sugars with cobalt(III)bis(phenanthroline)

Complexes of Co(III)bis(phenanthroline) with β-d-mannosamine and α-d-galactosamine can be isolated as the triiodide salts. The complex with d-mannosamine has the Δ-configuration at Co(III). Complexation with d-galactoamine gives the Δ- in excess over the Λ- complex, and the Δ-complex can be isolated chromatographically. Complexation involves cis-1-OH and 2-NH2 groups, eq, ax respectively with β-mannosamine and ax, eq respectively, with α-galactosamine, as with α-glucosamine, based on 1H NMR spectra. Galactosamine complexes in aqueous solution decompose to the free sugar, but the mannosamine complex is much more stable.