S. Walha

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

An organic–inorganic hybrid compound (C5H9N3)ZnCl4 · 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) Å, Z = 4, and V = 1212.8(12) Å3. The structure was solved using direct methods and refined by least-squares analysis [R 1 = 0.0484 and wR 2 = 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.

Electrical properties of the mixed compound K2.51(NH4)1.49Hg3Cl10.2H2O

Abstract Crystals of K2.51(NH4)1.49Hg3Cl10.2H2O undergo two phase transitions at T1=395 and T2=424 K. phase I—(395 K)→phase II—(424 K)→phase III These transitions have been detected by differential scanning calorimetry, impedance and modulus spectroscopy techniques. The first transition at T=395 K is related to NH4+ reorientation and H+ diffusion. The conductivity relaxation parameters associated with some K+/NH4+ and H+ conduction have been determined from an analysis of the M″/M″ max spectra measured in a wide temperature range. Transport properties in this material appear to be due to an K+/NH4+ and H+ ions hopping mechanism.

1-Methyl­piperazine-1,4-diium tetra­chloridozincate hemihydrate

The crystal structure of the title compound, (C5H14N2)[ZnCl4]·0.5H2O, is built up from discrete 1-methylpiperazinediium cations with chair conformation, tetrahedral tetrachloridozincate anions and uncoordinated solvent water molecules linked together by three types of intermolecular hydrogen bonds, viz. N—H⋯Cl, N—H⋯O and O—H⋯Cl.