Preparation, crystal structure, and physical characterization of a new hybrid material (C5H9N3)ZnCl4•H2O

An organic-inorganic hybrid compound (C5H9N3)ZnCl4 center dot H2O was synthesized by slow evaporation and characterized by single-crystal X-ray diffraction, differential scanning calorimetry, thermogravimetry, temperature-dependent X-ray powder diffraction, infrared spectroscopy, and some preliminary theoretical calculations of non-linear optic activity. The compound crystallizes in the non-centrosymmetric space group Pca21 with unit cell parameters: a = 22.714(5), b = 7.313(5), c = 7.301(5) angstrom, Z = 4, and V = 1212.8(12) angstrom 3. The structure was solved using direct methods and refined by least-squares analysis [R1 = 0.0484 and wR2 = 0.1255]. It is built from isolated [ZnCl4]2- anions, 2,5-diaminopyridinediium [C5H9N3]2+ cations, and water molecules which are connected by a 3-D hydrogen-bond network. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through four stages leading to a new crystalline anhydrous phases.