2-[1-(Salicyloylhydrazono)ethyl]pyridinium Chloride Dihydrate at 173K

The approximately planar molecule of the title compound, C₁₄H₁₄N₃O₂⁺.Cl⁻.2H₂O, is in an E conformation with respect to the C=N bond, with a C—C=N—N torsion angle of 179.5 (1)°. The maximum possible number of hydrogen bonds are formed in the crystal. The pyridinium H atom forms a hydrogen bond to a water molecule which is hydrogen bonded to the carbonyl O atom, requiring the pyridine ring to be rotated 180° compared to the unprotonated 2-formylpyridine analog. There is an intramolecular hydrogen bond involving the NH group on the chain and the hydroxyl O atom on the phenyl ring which, in turn, is hydrogen bonded to a Cl⁻ ion. Finally, a water molecule and chloride ion form a hydrogen-bonded square around a center of symmetry with O...Cl distances of 3.199 (2) and 3.206 (2) Å, and endocyclic angles of 91.17 (4)° and 88.83 (4)° at the O and Cl atoms, respectively.

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