CRYSTAL AND MOLECULAR-STRUCTURE OF ALLYL O-(SODIUM A-D-MANNO-2-OCTULOPYRANOSYLONATE)-(2-]8)-O-(SODIUM -ALPHA-D-MANNO-2-OCTULOPYRANOSIDONATE)-MONOHYDRATE

The (alpha-(2-->8)-linked Kdo disaccharide derivative allyl O-(sodium -D-manno-2-octulopyranosylonate)-(2-->8)-O-(sodium -alpha-D-manno-2-oc tulopyranosidonate)-monohydrate C19H28O15Na2.H2O, M(r)=542.32, is orth orhombic, P2(1)2(1)2(1) with a=9.229(1), b=12.036(1), c = 21.671(1) An gstrom and Z=4. The structure was solved by direct methods and refined to R = 0.040 for 2677 observed reflections. The torsion angles about the (2 --> 8)-glycosidic bond are stabilized by an intramolecular hydr ogen bond between the carboxylate group at the anomeric carbon atom of the terminal Kdo residue and the hydroxyl group O-17 of the second Kd o moiety.