Beschreibung:
<jats:p>The structures of three monohydrated halide salt forms of L-asparagine are presented, <jats:italic>viz.</jats:italic>L-asparaginium chloride monohydrate, C<jats:sub>4</jats:sub>H<jats:sub>9</jats:sub>N<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>
<jats:sup>+</jats:sup>·Cl<jats:sup>−</jats:sup>·H<jats:sub>2</jats:sub>O, (I), L-asparaginium bromide monohydrate, C<jats:sub>4</jats:sub>H<jats:sub>9</jats:sub>N<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>
<jats:sup>+</jats:sup>·Br<jats:sup>−</jats:sup>·H<jats:sub>2</jats:sub>O, (II), and L-asparaginium iodide monohydrate, C<jats:sub>4</jats:sub>H<jats:sub>9</jats:sub>N<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>
<jats:sup>+</jats:sup>·I<jats:sup>−</jats:sup>·H<jats:sub>2</jats:sub>O, (III). These form an isomorphous and isostructural series. The C—C—C—C backbone of the amino acid adopts a <jats:italic>gauche</jats:italic> conformation in each case [torsion angles for (I), (II) and (III) = −55.4 (2), −55.6 (5) and −58.3 (7)°, respectively]. Each cation features an intramolecular N—H...O hydrogen bond, which closes an <jats:italic>S</jats:italic>(6) ring. The extended structures feature chains of cations that propagate parallel to the <jats:italic>b</jats:italic>-axis direction. These are formed by carboxylic acid/amide complimentary O—H...O + N—H...O hydrogen bonds, which generate <jats:italic>R</jats:italic>
<jats:sub>2</jats:sub>
<jats:sup>2</jats:sup>(8) loops. These chains are linked by further hydrogen bonds mediated by the halide ions and water molecules to give a layered structure with cation and anion layers parallel to the <jats:italic>ab</jats:italic> plane. Compound (III) was refined as an inversion twin.</jats:p>