Synthesis and crystal structure of [CuCl(phen)2]3H3V10O28 · 7 H2O

The new compound, [CuCl(phen)₂]₃H₃V₁₀O₂₈ · 7 H₂O, was prepared by reaction of an aqueous KVO₃ solution (pH 3) with an aqueous solution of CuSO₄ · 5 H₂O in which 1,10‐phenanthroline (phen) and KCl were added. The crystal structure of the compound was determined, and the proton position in H₃V₁₀O₂₈^3– were calculated by the bond length/bond number method and also determined from difference electron density map. The protons are bound to colinearly arranged μ–OV₂ and μ–OV₃ groups which is the common protonation type in trihydrogen decavanadates. The structure crystallizes in P1 space group symmetry. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Elastic properties of the dithionates Na2S2O6 · 2 H2O,K2S2O6, Rb2S2O6, CaS2O6 · 4H2O and SrS2O6 · 4 H2O

Single crystals of the title compounds having optical quality and dimensions of several cm were grown from aqueous solutions. The elastic and thermoelastic constants were determined from ultrasonic resonance frequencies of thick plates. The true point symmetry of K₂S₂O₆ and Rb₂S₂O₆, which is screened by a hexagonal hypermorphy, could be clearly revealed to be trigonal (32) by the existence of the elastic constant c₁₄. In the case of CaS₂O₆ · 4H₂O and SrS₂O₆ · 4H₂O the constant c₁₄ of the specimens appeared too small to confirm the trigonal symmetry group required from electrooptic and non-linear optic effects unambiguously. The isotypy of K₂S₂O₂ and Rb₂S₂O₆ as well as that of CaS₂O₆ · 4H₂O and SrS₂O₆ · 4H₂O is confirmed by their elastic behaviour. The mean elastic stiffness of dithionates is closely related to that of the corresponding sulphates. In the vicinity of the second-order phase transition of K₂S₂O₆ near 235 K weak anomalies of the temperature derivatives of the longitudinal elastic stiffnesses are observed.     

On the (MgxNi1–x)SeO4 · 6 H2O and (MgxCu1–x)SeO4 · 5 H2O mixed crystal formation

Mixed crystals (Mg_xNi_1–x)SeO₄ · 6 H₂O and (Mg_xCu_1–x)SeO₄ · 5 H₂O have been prepared studying the solubility in the MgSeO₄–NiSeO₄–H₂O and MgSeO₄–CuSeO₄–H_2O systems at 25 °C. It has been shown that the monoclinic structure of MgSeO₄ · 6 H₂O is unstable and undergoes a change into tetragonal structure due to the included nickel ions (about 4 at %). The lattice parameters of (Mg_{xNi 1–x})SeO₄ 6 H₂O have been calculated. It has been established that the magnesium ions incorporate isodimorphously in the crystal structure of CuSeO₄ · 5 H₂O which could be an indication of the existence of MgSeO₄ · 5 H₂O isostructural with the triclinic CuSeO₄ 5 H₂O. The distribution coefficients of the salt components between the liquid and solid phases have been calculated.     

The Thermal Decomposition of Polyhalite K2SO4 · MgSO4 · 2 CaSO4 · 2 H2O

The thermal decomposition of polyhalite (K₂SO₄ · MgSO₄ · 2 CaSO₄ · 2H₂O) was investigated by DSC/TG and X-ray powder diffraction. The decomposition of the polyhalite starts at 285 °C in releasing the crystal water within one step. Simultaneously the decomposition of the polyhalite into anhydrite and two solid solutions of the compositions K₂SO₄ · 1.76 MgSO₄ · 0.24 CaSO₄ and K₂SO₄ · 0.64 MgSO₄ · 1.36 CaSO₄ is taking place. The mechanism of decomposition runs through K₂SO₄ · MgSO₄ CaSO₄. This phase reacts immediately to the solid solutions, mentioned above.     

EPR spectra of irradiated Na2Cr2O7 · 2 H2O crystals

The EPR spectra of X-irradiated Na₂Cr₂O₇ · 2 H₂O crystals grown from the aqueous solution at room temperature are studied. Three groups of lines are detected, which marked conventionally as C₁, C₂ and C₃. Each of the C₁ and C₂ line groups is a superposition of two doublets. The lines are interpreted as due to the Cr⁵⁺ ions in the distorted (stretched) oxygenous tetrahedron. The doublet structure is due to hyperfine interaction with nuclei of 1/2 spin which are protons of water. It is shown that the C₁ and C₂ line groups are due to the centers of the same type with different orientations in the lattice. The principal g-tensor values for these centres were as follows: g_z = 1.916, g_y = 1.978, g_x = 1.986.     

Crystal chemistry of the salts Me+Cl · Me2+Cl2 · 2 H2O

The crystal chemistry of the double salts Me⁺Cl · Me²⁺Cl₂ · 2 H₂O (where (Me⁺ = K, Rb, Cs; Me²⁺ = Mn, Fe, Co, Ni) is considered. It is concluded that these salts crystallize in three types of structures, the Me⁺ ion size being decisive for the structure type. Salts containing the large Cs⁺ ions crystallize in an orthorhombic structure in which [Me²⁺ (H₂O)₂Cl₄] octahedra form chains having common Cl⁻ corners. Salts with the smaller K⁺ ions crystallize in a tricline system, the [Me²⁺ (H₂O)₂Cl₄] octahedra being connected by a common Cl–Cl edge and forming dimers. When the intermediate in size Rb⁺ ions are present in the salts, either of the above structures is possible as well as a monoclinic structure which is intermediate in symmetry. The expected isostructure of the cesium salts was checked by studing the CsCl · NiCl₂ · 2 H₂O–CsCl · MnCl₂ · 2H₂O–H₂O system. A continuous series of mixed crystals is found.     

Synthesis of radial‐like ZnO structure by hydrothermal method with ZnSO4·7H2O and Zn(CH3COO)2·2H2O as zinc sources

Radial‐like ZnO structures were prepared using zinc sulfate (ZnSO₄·7H₂O) and zinc acetate [Zn(CH₃COO)₂·2H₂O] as zinc sources by a facile template‐free hydrothermal method in this paper. Structural and optical properties of radial‐like ZnO structures are characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV‐vis spectrophotometer and photoluminescence measurement (PL). It has been found that the distinct surface morphologies of radial‐like ZnO structures grown by different zinc sources. Slim radial‐like ZnO with a hexagonal wurtzite structure is grown by using ZnSO₄·7H₂O as zinc sources, whereas coarse radial‐like ZnO with zincite structure is achieved by zinc acetate. The UV‐vis absorption spectra of them both display an obvious and significant absorption in the ultraviolet region. The room temperature PL spectra of ZnO structures grown by two different zinc sources possess a common feature that consists of a strong ultraviolet (UV) peak and visible emission band.     

Study of optical and transport properties of K2CuCl4 · 2H2O single crystal

Optical absorption, transport properties and EPR of K₂CuCl₄ · 2H₂O single crystals have been studied. The optical absorption in UV, and visible region are characterized by a charge transfer band, and in the near infrared region at 3998, 4336, and 4480 cm⁻¹ are attributed to transitions between the stark levels of copper(II) ion in an extended octahedral crystal field. An anisotrophic ‘g’ value was observed with g_∥ = 2.12 and g_∥ = 2.24 by EPR method. The spin orbit coupling constant is found to be 500 cm₋₁. D.C. electrical conductivity measurements with temperature reveal an anisotropy characteristic of a two-dimensional layered structure and exhibit a first order irreversible structural phase-transition at 377 K, i.e. from tetragonal to monoclinic crystal system. X-ray diffraction studies and density calculations from the crystal structure data in both the phases suggest that the first order irreversible transition occurs following the loss of the two water molecules of hydration.     

Thermal expansion,pyroelectricity and linear optical properties of Li2SeO4·H2O and Li2SO4·H2O

Large single crystals of polar Li₂SeO₄·H₂O were grown at 343 K from aqueous solution. Temperature dependent thermal expansion coefficients of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were determined within the temperature range 133 K–313 K and coefficients of the pyroelectric effect within the temperature range 183–343 K. Refractive indices between 365 nm and 1530 nm as well as unpolarized absorption spectra of Li₂SeO₄·H₂O and Li₂SO₄·H₂O were measured and phase‐matching curves for second harmonic generation were calculated. Both compounds allow type I and type II phase‐matching at wavelengths from about 650 nm to the near infrared region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and X-ray structure studies of complex [Cu(o-phenanthroline)2 (saccharin)] · (saccharin) · 2 H2O

The title compound has been synthesized and its crystal structure determined at room temperature, M_r = 824.34, triclinic, space group P–1(2), a = 13.622(4), b = 13.770(4), c = 11.167(3) Å; α = 104.83(2), β = 110.01(2), γ = 62.04(2) degree; U = 1727.0(9) ų, Z = 2, D_calc = 1.59 g/cm³. The final R is 0.066 for 3299 independent observed reflections with I ≧ 3σ(I). The crystal structure consists of repeated [Cu(o-phen)₂(sac)]⁺ cations, non-coordinated saccharin anion and two lattice water. And the central ion Cu²⁺ forms a trigonal-bipyramidal stereochemistry.     

Structural features of a new [Fe(nicotinamide)2(H2O)4]·[Fe(H2O)6]·(SO4)2·2H2O complex

A new nicotinamide complex of Fe(II) cation was prepared by reaction between ferrous sulfate and nicotinamide in aqueous solution. The complex was characterized on the basis of elemental analysis, FT IR and UV–VIS spectroscopy, electrochemistry (cyclic voltammetry) and X–ray crystallography. The complex consists of the molecular composition of [Fe(nicotinamide)₂(H₂O)₄]· [Fe(H₂O)₆]·(SO₄)₂·2H₂O. The complex crystallizes in the monoclinic space group P 2₁/c [a = 12.862(3), b = 7.110(3), c = 16.382(3) Å; β = 95.79(2)°]. It has been proven that nicotinamide is coordinated to Fe(II) through the nitrogen atom of its heterocyclic ring. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

The crystal and molecular structure of hydrazine-N,N′-dicarbonic-acid-di-(4-chlorophenyl)-ester Dihydrate,C14H10Cl2N2O4 · 2 H2O

The crystal and molecular structure of the title compound has been determined by X-ray diffraction techniques. It crystallizes in the monoclinic space group C2/c with cell parameters a = 30.719(8), b = 5.016(3), c = 10.946(8) Å, and β = 106.08(3)°. The structure was solved by direct methods and refined to R = 0.038. The drug molecule consists of two chemically identical parts, symmetry related by a two-fold axis coinciding with that of the space group. Hydrogen bonds connect water and drug molecules forming infinite layers parallel to the y, z-plane.     

Structure of monoclinic acridine orange hydrochloride monohydrate,C17H19N3 · HCl · H2O

M_r = 319.82, monoclinic P2₁/a, Z = 4, a = 14.545(5), b = 15.562(6), c = 8.538(4) Å, β = 120.66(3)°, V = 1662(1) ų, D_m = 1.27 Mgm⁻³, D_x = 1.278 Mgm⁻³, λ(MoKα) = 0.71069 Å, μ(MoKα) = 0.24 mm⁻¹, T = 297 K. Final R = 0.049 for 1485 observed reflections. All hydrogen atoms were located and refined isotropically. Bond lengths (σ = 0.004 Å) and angles (σ = 0.3°) are normal. The substance is a derivative of acridine. The structure consists of chloride anions, bisdimethylaminoacridinium cations and water molecules. In the solid state the molecules are approximately planar. Pairs of cations form dimers with parallel planes connected by an I inversion centre and plane distances of 3.474 Å. They overlap with partial areas of all three six membered rings.     

Electrical Conductivity and Thermal Dehydration Studies of Mixed Single Crystals of BaCu(C2O4)2 · 6 H2O,Ba1–xCuxC2O4 · 4 H2O and Ba1–2x(NH4)2xC2O4 · 4 H2O

The measurement of electrical conductivity for the investigation of the number of water molecules present in the mixed crystals of barium copper oxalate and barium ammonium oxalate lattice have been carried out in the temperature range 30 to 450 °C. The dehydration temperature and the number of water molecules removed out of the structure at a particular temperature is estimated from the sharp increase in conductivity at these points. The almost steep increase of conductivity is attributed to the increase in the number of mobile charge carriers H⁺ and OH^– ions generated from the escaping water molecules. The study of electrical conductivity in association with the thermal behaviour has been used to understand the mechanism of conduction.     

The crystal structure of zinc azide · 2-methylpyridine at 98 K

The crystal structure of the title compound has been determined by single crystal X-ray diffraction methods at 98 K. Zinc azide · 2-methyl pyridine crystallizes in the space group P1 with a = 6.028(2) Å, b = 7.610(3) Å, c = 10.052(4) Å, α = 92.81(3)°, β = 101.08(2)·, γ = 94.64(3)° and Z = 2. Least-squares refinement gave an R value of R_w = 0.039 for 2096 observed reflections. Each zinc atom is surrounded by four nitrogen atoms of different azide groups and one nitrogen atom of the pyridine adduct in a distorted trigonal bipyramidal fashion. The ZnN₅-polyhedra share common edges to form chains along the crystallographic a-axis.