The Characteristics of the Mixed Crystals of the K2SO4-(NH4)2SO4-H2O System at 298 K

Equilibrium studies of the K₂SO₄-(NH₄)₂SO₄-H₂O system at 298 K have been conducted. The isotherm of solubility and the curve of distribution have been mathematically described. The parameters of the crystal lattice and the enthalpy of crystallization of the [K_x(NH₄)_1-x]₂SO₄ solid solutions as a function of their composition have been presented.     

Crystal structure of NH3(CH2)2NH3(BiI4)2·4H2O

The ethylenediammonium bis tetraiodobismuthate(III) tetrahydrate salt is monoclinic with the following unit cell dimensions:a=7.476(3)Å,b=13.194(3)Å,c=13.916(9)Å, β=95.22(6)°, space groupP2₁ lc withZ=2. The structure consists of disordered ethylenediammonium cations, water molecules and polynuclear anions in which slightly distored [BiI₆]^3? octahedra sharingcis edges are interconnected into chains. The [BiI₄]^? anions are connected through O(W2)?H...I hydrogen bonds, so that infinite two dimensional chains parallel to thea axis with anionic period [BiI₄(H₂O)]^? are formed in the structure. These chains are themselves interconnected by means of the O?H...I and N...O(I) bonds originating respectively from the water molecules and the ethylenediammonium entities, forming a three-dimensional network.     

Preparation and studies of new crystals in the K3H(SO4)2-(NH4)3H(SO4)2-H2O system

To elucidate the effect of isomorphic substitution on the kinetics of phase transitions, single crystals of (K _x (NH₄)_1?x ) _m H _n (SO₄)_{(m + n)/2} · yH₂O solid solutions are grown from the K₃H(SO₄)₂-(NH₄)₃H(SO₄)₂-H₂O system, whose end members are known to undergo superprotonic phase transitions of fundamentally different kinetics. The chemical composition of the single crystals grown is determined by energy dispersive X-ray microanalysis. The thermal and optical behavior of (K,NH₄)₉H₇(SO₄)₈ · H₂O single crystals is studied in the temperature range 295–420 K and the crystal structure at 295 K is determined. A comparison of the results of the studies with data for crystal K₉H₇(SO₄)₈ · H₂O published earlier shows that the substitution of ammonium for potassium atoms lowers the temperature of the structural phase transition by 8 K.     

The Synthesis and Crystal Determination of 3-Hydroxy-4-(4-methoxyphenyl)-5-(2-nitrophenyl)furan-2(5H)-one

Abstract  

The title compound, C₁₇H₁₃NO₆, was synthesized and structurally characterized by elemental analysis, MS, ¹H NMR and single crystal X-ray diffraction. It crystallizes in monoclinic system space group C 2/c with a = 27.981(6) ?, b = 12.996(3) ?, c = 8.0900(16) ?, β = 91.06(3)°, V = 2941.4(10) ?³, Z = 8, R ₁ = 0.0675, wR ₂ = 0.1626, and T = 298(2) K. The X-ray structure determination revealed that the center furanone ring is nearly coplanar with p-methoxybenzene ring and forms a dihedral angle of 87.2(1)° with the nitrobenzene ring. O–H···O Intermolecular hydrogen bonds link pairs of molecules into centrosymmetric dimers, making a graph set motif of R ₂²(10). The dimers are further assembled into a chain of edge-fused R ₄⁴(34) rings running along the [001] direction. The final three-dimensional supramolecular architecture is stabilized by weak π–π interactions.     

Crystal structure of pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate, (NH3(CH2)2NH3)5(Sb2Cl11)2·4H2O

The pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate salt is monoclinic with the following unit cell dimensions:a=16.271(5) Å,b=13.004(4) Å,c=13.932(4) Å, β=111.72(2)°, space groupP2₁/c withZ=2. The structure was solved by Patterson methods and refined to a finalR value of 0.023 for 4435 reflections withF ₀>4σ(F ₀). The structure shows a layer arrangement perpendicular to thea axis: planes of the [Sb₂Cl₁₁]⁵⁻ bioctahedra alternate with planes of [NH₃(CH₂)₂NH₃]²⁺ dications. The [Sb₂Cl₁₁]⁵⁻ bioctahedra are connected through O−H...Cl hydrogen bonds, such that infinite chains of composition [Sb₂Cl₁₁(H₂O]_n ⁵ⁿ⁻ are formed in the structure, parallel to the twofold axis. These chains are themselves interconnected by means of N−H...Cl and O−H...Cl bonds originating from the [NH₃(CH₂)₂NH₃]²⁺ entities and the water molecules, respectively, and form a threedimensional network.     

X-Ray Radiography Investigations of Solid Solutions with Limited Miscibility in K2SO4-(NH4)2SO4-H2O System

The measurements of crystal lattice parameters (a, b, c) were conducted and the volumes (v) and densities (∂) of solid solutions of (K, NH₄)₂SO₄ were calculated. It was established that in the system K₂SO₄-(NH₄)₂SO₄-H₂O at 25 °C mixed crystals with limited miscibility were formed. The gap in the continuity of solid solutions occurred in a very narrow range of concentrations of (NH₄)₂SO₄ in mixed crystals, namely from 69.5 to 72.5%. In order to get the confirmation of the above, the detailed equilibrium investigations nearby the peritonic point (the concentration of K₂SO₄ −3.32%, the concentration of (NH₄)₂SO₄ −38.66%) were carried out.     

Surface Evolution at the Phase Transitions in (NH4)3H(SeO4)2 Crystals

Crystallography Reports - The (NH4)3H(SeO4)2 crystals in the temperature range of 296–343 K and the evolution of their surface at phase transitions have been studied by atomic force...     

Crystal structure of (NH4)5Sc3F14

The equilibrium in the (NH₄)₃ScF₆-NH₄HF₂-H₂O system in the range of hydrodifluoride ammonium solution concentrations of 0.05–3.5 mol/L at temperatures of 18 and 90°C is studied. The composition of solid phases in equilibrium is analyzed using elemental analysis, X-ray diffraction, and neutron diffraction. A new phase, (NH₄)₅Sc₃F₁₄ with a tetragonal lattice (sp. gr. I4₁/a, unit-cell parameters a = 0.80843 nm and c = 2.5177 nm), is found at fluoride ion concentrations in the solution of ≤1.06 mol/L at 18°C and 2.92–3.01 mol/L at 90°C; the crystal structure of this phase is determined.     

Synthesis and Crystal Structures of 4-(3-Nitropyridin-2-ylamino)phenol and 4-(3-Aminopyridin-2-ylamino)phenol

Abstract  

The title compounds, 4-(3-nitropyridin-2-ylamino)phenol (I) and 4-(3-aminopyridin-2-ylamino)phenol (II), are two intermediates for the synthesis of a potential antitumor agent ABT-751. The reaction of 4-aminophenol with 2-chloro-3-nitropyridine yielded I which was converted into II by reduction. Instead of the Pd/C catalytic hydrogenation described in many literature, reduction with cheap sodium sulfide in aqueous media was utilized for shorting the reaction time and simplifying the operation. The crystal structures of the resultant compounds were determined by single-crystal X-ray diffraction. The compound I is crystallized in P2₁/c space group of monoclinic system, with a = 11.5236(19) ?, b = 8.7389(17) ?, c = 10.684(3) ? and α = 90.00°, β = 107.76(3)°, γ = 90.00°. The compound II is crystallized in Cc space group of monoclinic system, with a = 10.688(2) ?, b = 14.2181(18) ?, c = 7.9836(15) ? and α = 90.00°, β = 125.801(7)°, γ = 90.00°. In both crystal structures, the intermolecular N–H–O and O–H–N hydrogen bonds link the molecules, which effectively stabilize the structures.     

Crystal and molecular structure of (E)-2-t-butyl-3(3′-t-butyldimethylsiloxy)propyl-2-cyanocyclobutanone

The title compound crystallizes in the monoclinic space group P2₁/a, witha+12.906(9).b+11.604(2).c+14.631(9) Å, β=108.70(3)° andZ+4. The structure was solved by direct methods from diffractometer data and refined to a finalR value of 0.057 for 2020 independent reflections. The structure analysis confirms the cis disposition of the bulky substituents and indicates a puckered four-membered ring with a dihedral angle of 18.5° as expected for a non-centrosymmetrically substituted cyclobutanone.     

Synthesis and Crystal Structure of Heptyl 3-(3,4-dihydroxyphenyl)-2-propenoate

Abstract  The title compound, C₁₆H₂₂O₄, synthesized by modified Knoevenagel condensation of protocatechualdehyde with monoheptyl-malonate and recrystallized from benzene, was confirmed by single-crystal X-ray diffraction (CCDC 272827). The compound crystallizes in triclinic space group Pī with cell parameters a = 5.296(3) ?, b = 10.711(13) ?, c = 13.870(4) ?, α = 98.84(7)°, β = 90.97(4)°, γ = 96.77(7)° and Z = 2. The structure is the E isomer and its packing is stabilized by intermolecular O–H···O and C–H···O hydrogen bonds. Index Abstract  The title compound, C₁₆H₂₂O₄, synthesized by modified Knoevenagel condensation, was confirmed by single-crystal X-ray diffraction showing its structure is in E isomer and its packing is stabilized by hydrogen bonds.      

Crystal and molecular structure ofl-3-(2-acetamido-2-ethoxycarbonyl)ethylindole

l-3-(2-Acetamido-2-ethoxycarbonyl)ethylindole is monoclinic:a = 11.469(8),b = 8.088(6),c = 8.457(6) Å, = 106.45(7) °,Z = 2,P2₁. The structure has been solved by direct methods with CuK three-dimensional photographic data, and refined by full-matrix least squares toR = 0.097 for 1390 observed reflections. The structure is stabilized by intermolecular N-H...O hydrogen bonds. The indole ring of the molecule is planar within experimental error.Contribution No. 440 from the Department of Crystallography and Biophysics, University of Madras, Guindy Campus Madras-600025, India.     

2-甲基4-(4-(吡啶-3-乙炔基)苯基)-3-丁炔-2-醇的合成及晶体结构

由1,4-二碘代苯出发,经过两步Sonogashira偶联反应合成了标题配合物2-甲基4.(4-(吡啶-3-乙炔基)苯基)-3-丁炔-2-醇.通过1H NMR、13C NMR核磁共振、Ⅹ-射线单晶衍射等手段对化合物的结构进行了表征.结果表明,该化合物晶体属于单斜晶系,空间群为P21/c.晶体学参数:a=3.3321 (4) nm,b=1.00539(11) nm,c=0.89158(10) nm,α =90.00°,β=92.442(2)°,y=90.00°,V=2984.2(6) nm3,Z =4.     

Crystal structure of 1-(2-hydroxyphenyl)-3-(2-thiomethoxyphenyl)-1,3-propanedione,C16H14O3S

The crystal structure of the enol tautomer of 1-(2-hydroxphenyl)-3-(2-thiomethoxyphenyl)-1,3-propanedione C₁₆H₁₄O₃S, was determined from X-ray crystallography. The finalR value was 5.99% based on 1945 unique observed reflections. The crystals are monoclinic,P2₁/c, witha=7.406(6),b=8.585(6),c=21.992(4) Å,=93.42(2),D _c =1.36 g cm^–3 forz=4. The compound is present in the solid state as a unique enol tautomer.There are two short, intramolecular OO contacts of 2.553(4) and 2.577(4) Å. Both the phenol and the enol H atoms are asymmetrically located with respect to the O atoms.     

Molecular structure of trans-[Co(NH3)4(NH2CH3)Cl](ClO4)2

The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I>2(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH₃)₄(NH₂CH₃)Cl](ClO₄)₂ molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.     

3-Aryloxypropiononitriles Intermediates: Crystal and Molecular Structure of 2- and 4-(2-Bromoethoxy)diphenylmethanes

The crystal structure of 2- and 4-(2-bromoethoxy)diphenylmethanes ( I and II respectively), intermediates in a novel synthesis of substituted 3-aryloxypropiononitriles, have been determined by single crystal X-ray diffraction at room temperature (r.t.) and at 150K. No significant changes in the crystal structure of I and II have been observed in going from r.t. to 150K. In both compounds the bromoethoxy group presents a gauche conformation and shows a short Br.O intramolecular interaction that allows to explain the very good reaction yields obtained in the novel synthesis. The three-dimensional structure of I is stabilized by two intermolecular hydrogen bonds and that of II by six. This difference in the crystal packing of I and II explains the variation in the m.p. The analysis of ¹H and ¹³C NMR spectra suggests that the molecular conformations in solution are similar to those found in solid state.     

Organometallic Vapour Phase Epitaxy of Galliumnitride Using Ga(CH3)3 · N(CH3)3-Adduct Pyrolysis

Epitaxial layers of GaN have been grown on {1102} sapphire in atmospheric OMCVD system using Ga(CH₃)₃ · N(CH₃)₃ adduct and NH₃ as reactants. Optimum growth conditions for crystallographically perfect layers have been found at temperatures between 850 and 1000 °C. With increasing temperature the growth rate decreases whereas the concentration of free carriers increases. In photoluminescence spectra only the donor-acceptor pair recombination could be found. It is concluded that the donor oxygen (O_N) and the acceptor carbon (C_N) are the dominant impurities.     

Crystal and molecular structures of 1-(2-carboxypropan-2-ylamino)-3-(1-naphthyloxy) propan-2-ol (1) (C17H21NO4) and 1-(2-carbamoyl propan-2-ylamino)-3-(1-naphthyloxy) propan-2-ol (2) (C17H22N2O3)

The crystal structures of two new-adrenergic antagonists, derivatives of propranolol containing 2-methylalanine fragment are described in this paper. The space groups and unit-cell parameters are: compound1 (C₁₇H₂₁NO₄): monoclinic, space groupP2₁/n,a=5.787(1),b=18.703(4),c=23.526(5)Å,=96.49(2)°; compound2 (C₁₇H₂₂N₂O₃): triclinic, space groupP¯1,a=8.321(1),b=10.121(1),c=10.368(1)Å,=109.49(1)°,=90.49(1)°, =103.48(1)°. The structures were solved by direct methods and refined with full matrix least-squares techniques toR indices of 0.055 and 0.049, respectively. The molecules of compound1 exist in the crystal as dual ions. The molecules of compound2 are compact and their external chain is twisted in a characteristic way (similar to that found in peptides).