Bis(L-serinium) oxalate dihydrate: polymorph II

A corrected and improved structure of the polymorph II of 2C(3)H(8)NO(3)(+)center dot C(2)O(4)(2-center dot)2H(2)O, based on single-crystal data, is presented. The structure is refined with anisotropic displacement parameters for all non- H atoms and all H atoms are located. Due to the charged moieties, the structure is classified as a molecular salt. Intermolecular O-H center dot center dot center dot O-, O-H center dot center dot center dot O and N+-H center dot center dot center dot O- hydrogen bonds link the components of the structure. The L-serinium cations and oxalate anions form a network of channels in [100] direction, filled with the water molecules of crystallization. The dihedral angle between the CO2 units of the oxalate dianion is 10.2 (3)degrees