Bis(l-serinium) oxalate dihydrate: polymorph II

A corrected and improved structure of the polymorph II of 2C(3)H(8)NO(3) (+)·C(2)O(4) (2−)·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⋯O(−), O—H⋯O and N(+)—H⋯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 CO(2) units of the oxalate dianion is 10.2 (3)°