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

Abstract 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-NH 2 groups, eq , ax respectively with β -mannosamine and ax , eq respectively, with α -galactosamine, as with α -glucosamine, based on 1 H NMR spectra. Galactosamine complexes in aqueous solution decompose to the free sugar, but the mannosamine complex is much more stable.