Crystal Structure of a Novel Proton Transfer Compound: Guanidinium 4-Hydroxy-2,6-pyridinedicarboxylate Monohydrate

Abstract

The crystal structure of (GH)⁺(hypydcH)^-·H₂O, (G = guanidine, hypydcH₂ = 4-hydroxy-2,6-pyridinedicarboxylic acid) has been determined by the X-ray diffraction method. This compound crystallizes in the triclinic system, space group P1, with two formula units in the unit cell. The unit-cell parameters are: a = 6.6451(8)Å, b = 7.9643(9)Å, c = 11.1963(13)Å, with α = 87.920(3)°, β = 75.574(3)° and γ = 72.796(2)°. The final R value is 0.0764 for 1121 measured reflections. Proton transfer results in the formation of a self-associated system consisting of cationic and anionic units connected through H-bonding and ion-pairing simultaneously.