Crystal and molecular structure of allyl O-(sodium 3-deoxy-α-d-manno- 2-octulopyranosylonate)-(2 → 8)-O-(sodium 3-deoxy-α-d-manno- 2-octulopyranosidonate)-monohydrate

The α-(2 → 8)-linked Kdo disaccharide derivative allyl O-(sodium 3-deoxy-α-d-manno- 2-octulopyranosylonate)-(2 → 8)-O-(sodium 3-deoxy-α-d-manno-2-octulopyranosidonate)-monohydrate C19H28O15Na2·H2O, Mr = 542.32, is orthorhombic, P212121 with a = 9.229(1), b = 12.036(1), c = 21.671(1) Å, 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 hydrogen bond between the carboxylate group at the anomeric carbon atom of the terminal Kdo residue and the hydroxyl group O-17 of the second Kdo moiety.