title: Strong asymmetric hydrogen bonding in 2-(oxamoylamino)ethylammonium oxamate-oxamic acid (1/1).
abstract: The title compound, C(4)H(10)N(3)O(2)(+) x C(2)H(2)NO(3)(-) x C(2)H(3)NO(3), contains at least 11 distinct hydrogen-bond interactions showing a great variety of bond strengths. The shortest and strongest hydrogen bond [O...O = 2.5004 (12) A] is found between the uncharged oxamic acid molecule and the oxamate monoanion. The grouping formed by such a strong hydrogen bond can thus be considered as a hydrogen bis(oxamate) monoanion. It lacks crystallographic symmetry and the two oxamate groups have different conformations, showing an asymmetric hydrogen-bond interaction. Significantly, the asymmetry allows us to draw a direct comparison of site basicity for the two inequivalent carboxylate O atoms in the planar oxamate anion. The constituent molecular ions of (I) form ribbons, where all amide and carboxylate groups are coplanar. Graph-set analysis of the hydrogen-bonded networks reveals the R(2)(2)(10) and R(2)(2)(9) homodromic nets as important structure-directing motifs, which appear to be a common feature of many oxamate-containing compounds.
authors.affiliation: WestCHEM, Department of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland.
authors.forename: Marta
authors.initials: M
authors.lastname: Martinez Belmonte
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Price
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D010072:Oxamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: C548567:2-(oxamoylamino)ethylammonium oxamate-oxamic acid; D007477:Ions; D010072:Oxamic Acid