Complexes of cobalt(III) with D-glucosamine and amines

Abstract d -Glucosamine and ammonia, 1,2-ethylenediamine, or 1,10-phenanthroline form complexes with Co(III) * . The complexes are: [Co(NH 3 ) 3 ·H 2 O· d -glucosamine] 3+ , [Co(en) 2 · d -glucosamine] 2+ and [Co(phen) 2 · d -glucosamine] 3+ . Formation of the last two complexes is stereospecific with Co(III) with predominance of the Δ over the Λ diastereomer. The Δ and Λ diastereomers of the ethylenediamine and phenanthroline complexes with d -glucosamine were separated and their configurations about Co(III) assigned from the CD and ORD spectra. The ethylenediamine complex has p K a ∼ 3.4 and is more acidic than the other complexes, pointing to coordination of the alkoxide residue at position 1 of glucosamine.