Influence of the thickness of [N(CH3)4]2Zn0.75Mn0.25Cl4 crystal on the phase-transition temperature

The change in the phase-transition temperature of [N(CH₃)₄]₂Zn_0.75Mn_0.25Cl₄ crystal as a function of its size (3500 μm-1 μm) has been investigated. It is established that a decrease in crystal sizes along the spontaneous-polarization axis is accompanied by several effects: a shift of the initial phase-incommensurate phase transition point to higher temperatures, an increase in the temperature range of existence of incommensurate phase, an increase in the temperature range of existence of metastable states of incommensurate structure, the occurrence of new long-period commensurate phases, and an increase in phase-transition temperature hysteresis at T _c and T ₃. The possibility that a size effect exists in the phase diagram of this crystal is discussed.     

Hydrogen-bonded coordination network in crystal structures of [Cu(3-PM)4Cl2] and [Cu(4-PM)4Cl]Cl, (PM = pyridylmethanol)

The crystal and molecular structures of [Cu(3-PM)₄Cl₂] (1) and [Cu(4-PM)₄Cl]Cl (2) have been determinated by X-ray crystallography. Complex 1 crystallizes in the triclinic system, space group P–1, with lattice parameters a = 7.972(2) Å, b = 8.293(2) Å, c = 10.707(2) Å, = 105.73(3)°, = 90.04(3)°, = 110.38(3)°, and Z = 1 at 100 K. The coordination geometry of each Cu atom is approximately octahedral formed by four nitrogen atoms of pyridine rings of 3-pyridylmethanol molecules in the equatorial plane and two chlorine atoms occupying the axial positions. The O—HsO, C—HsCl, and O—HsCl intermolecular hydrogen bonds and s stacking link the molecules in 3-D hydrogen-bonded coordination network. Complex 2 crystallizes in the tetragonal system, space group P4/n, with lattice parameters a = 10.464(1) Å, c = 11.339(2) Å, and Z = 2 at 217 K and a = 10.352(1) Å, c = 11.201(2) Å, and Z = 2 at 293 K. The coordination geometry of Cu atom in the [Cu(4-PM)₄Cl]⁺ ion is approximately square pyramidal formed by four nitrogen atoms of pyridine rings of 4-pyridylmethanol molecules in equatorial plane and one chlorine atom in axial position. The O—HsCl and C—HsCl intermolecular hydrogen bonds link the molecules in 2-D hydrogen-bonded coordination network.     

Molecular structure of AlH3[N(CH2CH2)3CH]2

Reaction of AlH₃[N(CH₂CH₂)₃CH] with hexamethyltrisiloxane, (OSiMe₂)₃, gives rise to the bis-quinuclidine complex AlH₃[N(CH₂CH₂)₃CH]₂, which has been characterized by ¹H and ¹³C NMR spectroscopy and X-ray crystallography. The molecular structure of AlH₃[N(CH₂CH₂)₃CH]₂ consists of a trigonal bipyramidal aluminum with axial coordination of the quinuclidine ligands. Crystal data: orthorhombic, space group Pbcn, a = 10.6895(9), b = 12.266(1), c = 12.3794(9) Å, V = 1623.2(2) ų, and Z = 4.     

N-亚水杨基正丁胺锌配合物的合成、谱学表征和晶体结构

以乙酸锌、正丁胺及水杨醛为原料在甲醇介质中反应,合成得到了席夫碱配合物N-亚水杨基正丁胺锌[Zn(CH3CH2 CH2CH2N=CHC6H4O)2],用元素分析、红外光谱、核磁共振氢谱和热重分析进行了谱学表征,培养了该配合物的单晶,并通过单晶X射线衍射测得其晶体结构为四方晶系, 空间点群为P-4,a=1.4380(2)nm,b=1.4380(2)nm,c=0.53803(18)nm,α=β =γ=90°,V=1.1126(4)nm3 ;Dc =1.247 g/cm3;Z=2;F(000) = 400;μ =1.12mm-1.锌离子位于变形四面体的中心,分别与两个席夫碱N原子和两个酚氧负离子形成配合物.     

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.     

Synthesis and molecular structure of [Al(CH3)2]2[C10H22N4] [Al(CH3)3]2: Condensation product of trimethylaluminum and a multidentate open-chain amine

The crystalline condensation product [Al(CH₃)₂]₂[C₁₀H₂₂N₄][Al(CH₃)₃]₂ is prepared from reaction of the multidentate open-chain amine 1,4-bis(3-aminopropyl)piperazine with trimethylaluminum in methylene chloride. The compound crystallized in the monoclinic space groupC2/c with unit cell parametersa=25.166(12),b=7.268(4),c=17.316(4) Å,=115.3(4)°, andD _c =1.06 g cm^–3 forZ=4. Least-squares refinement based on 1054 observed reflections with intensitiesI 3(I) in the range 2<2<45° led to a finalR factor of 0.053 (R _w =0.064). The title compound resides on a crystallographic center of symmetry with independent Al-N distances of 1.889(5), 2.058(5), and 2.030(5) Å.     

Synthesis and structure of zinc iodide complex with thiocarbamide, [Zn(CH4N2S)2I2]

A complex compound of zinc iodide with thiocarbamide [Zn(CH₄N₂S)₂I₂] is obtained and its structure is studied by X-ray diffraction. Crystals are monoclinic, a = 10.494(2) Å, b = 7.473(2) Å, c = 14.871(4) Å, β = 91.354(18)°, V = 1165.9(5) ų, space group P2₁/c, Z = 4. The structural unit of the crystal is molecular complex [Zn(CH₄N₂S)₂I₂], in which the zinc atom is coordinated by sulfur atoms of two thiocarbamide molecules and two iodine atoms.     

Polarization switching in (CH3NH3)5Bi2Cl11 ferroelectric crystals

The polarization switching in methylammonium chlorobismuthate, (CH₃NH₃)₅Bi₂Cl₁₁, single crystal was investigated by optical observations of the domain structure and switching current registration. It is shown that defects introduced during crystal growth influence the polarization switching kinetics. For the analysis of switching current data the statistical Avrami model of phase transformation kinetics was employed. Direct observation of the domain structure enabled us to verify the assumptions of the Avrami model in the case of non‐uniform (CH₃NH₃)₅Bi₂Cl₁₁ crystals. It is found that application of this model to non‐uniform crystals can yield physically unclear values of some fitting parameters; e.g. the effective domain growth dimension is not constant with respect to the electric field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X-ray diffraction study of the heterovalent copper compound [Cu4(OH)4 Bipy 4][Cu2(B10H10)3] · 4CH3CN

X-ray diffraction studies of three samples of the [Cu₄(OH)₄ Bipy ₄][Cu₂(B₁₀H₁₀)₃]·4CH₃CN crystals reveal a small amount (4?C6%) of the second component, which is related to the main component by a mirror pseudoplane. An analysis of the geometric structure and mutual arrangement of complex cations [Cu₄(OH)₄ Bipy ₄]⁴⁺ and anions [Cu₂(B₁₀H₁₀)₃]^4? in the cell shows that replacing structural elements by their mirror equivalents results in insignificant steric conflicts. The existence of this minor crystal component can be attributed to point substitution defects or a separate twin individual.     

Solvent-controlled structures. Synthesis and characterization of complexes Cu(L)2(CH3COO)2 and [Cu2(μ-CH3COO)4(L)2](L)2 [L = N-(4′-methylaniline)-4-pyridinecarboxamide]

Two complexes Cu(L)₂(CH₃COO)₂ (1) and [Cu₂(μ-CH₃COO)₄(L)₂](L)₂ (2) (L = N-(4′-methylaniline)-4-pyridinecarboxamide) have been prepared and their crystal structures have been determined by single-crystal X-ray diffraction. The complexes are obtained by using the same raw materials and reaction conditions except solvents. The presence or absence of water controls the coordination mode to give rise to different structures. The structure of 1 has a triclinic space group P-1 with a = 8.381(3) ?, b = 8.545(4) ?, c = 11.357(5) ?, α = 110.654(6)°, β = 102.388(7)°, γ = 97.889(7)°, V = 722.9(5) ?³, and Z = 1. The structure of 2 has a triclinic space group P-1 with a = 9.121(3) ?, b = 9.454(3) ?, c = 17.233(5) ?, α = 77.374(5)°, β = 89.827(6)°, γ = 74.342(6)°, V = 1393.8(7) ?³, and Z = 1. Supramolecular assemblies have also been found via noncovalent bonds such as hydrogen bonds, π–π stacking interactions.     

配合物[Zn(CH3COO)2(C7H6N2S)2]的合成、晶体结构及表征

用乙酸锌和2-氨基苯并噻唑为原料在甲醇介质中反应制得了配合物[Zn(CH3COO)2(C7H6N2S)2],用元素分析、红外光谱、核磁共振氢谱和热重分析对其进行了表征,用X射线单晶衍射仪测定了其晶体结构,其晶体属于正交晶系,空间群为Pna2(1),晶胞参数分别为a=0.8547(3)nm,b=2.7586(8)nm,c=0.9066(3)nm,α=β=γ=90°,V=2.1376(11)nm3;Dc=1.503g/cm3;Z=4;F(000)=992;μ=1.375mm-1.     

孔道结构钒铝磷酸盐(NH3CH2CH2NH2)[(VO)Al(PO4)2]的水热合成及热稳定性

用XRD,TG-DTA,FT-IR和SEM对水热法合成的孔道结构钒铝磷酸盐(NH3CH2CH2NH2)[(VO)Al(PO4)2]进行了热性能表征.该化合物中有机组份的分解温度,在氧化气氛中为305～529℃,在惰性气氛中为411～593℃.有机组分的分解逸出导致了结构的破坏,但晶体的微形貌没有发生明显的变化;温度继续升高,发生相变.该化合物热稳定性较其它含有机模板的孔道结构钒磷酸盐要高,主要原因在于结构中存在[AlO4]和[PO4]共顶连接而成的一维链,这种链增加了骨架的强度.     

Synthesis and structural characterization of [Ni(Me2NCH2CH2CH2N=CHC6H4O)2]

The synthesis, properties, and X-ray crystal structure of a Ni(II) complex of the tridentate Schiff base ligand Me₂NCH₂CH₂CH₂N=CHC₆H₄OH(LH) are described. The complex crystallizes in the monoclinic space group P2₁/c, with a = 10.180(2), b = 15.169(3), c = 15.293(4) Å, = 106.69(2)°, and Z = 4. The Ni atom shows a distorted fac-octahedral geometry, with the two Ni—N(Me₂) bonds being significantly longer than the two Ni—N(imino) bonds, 2.284(9), 2.310(9) vs. 2.051(2), 2.055(2) Å.     

Synthesis and crystal structure of [Cu2(NO3)4L2(BIPY)2 (H2O)3]·H2O (L = N,N′-bis(4-pyridylmethyl) isophthalamide

The synthesis and molecular structure of the title compound is reported. There are two different Cu atoms in separate chains which are linked to form double-stranded chains. Each Cu has a distorted octahedral coordination geometry. The structure has a triclinic space group P-1 with a = 11.0764(5), b = 15.9276(7), c = 18.2000(7) Å, V = 3197.9(2) ų, and Z = 2.     

Theoretical phase diagrams for [N(CD3)4]2ZnCl4 crystal

A theoretical phase diagram of [N(CD₃)₄]₂ZnCl₄ crystal is constructed in the plane of two thermodynamic-potential coefficients. The orientation of the temperature (T) and pressure (P) axes is chosen in the diagram. The first diagram is used as a basis to construct the second theoretical T-P phase diagram, expanded to the region of weak negative pressures for nondeuterated [N(CH₃)₄]₂ZnCl₄ crystal. It is suggested that this region can be observed for deuterated [N(CD₃)₄]₂ZnCl₄ crystal.     

Crystal structure investigation of [Mn(3-CH3C5H4N)2(N3)2(H2O)2]

The crystal structure of the title compound has been determined by single crystal X-ray diffraction methods. [Mn(3-CH₃C₅H₄N)₂(N₃)₂(H₂O)₂] crystallizes in the space group P 1 with a = 7.444(2) Å, b = 7.691(2) Å, c = 8.926(3) Å, α = 99.82(3)°, β = 108.80(2)°, γ = 114.99(2)° and Z = 1. Least squares refinement gave a R value of R_w = 0.046 for 1414 observed reflections. The manganese atom in the title complex is octahedrally coordinated by two oxygen atoms of the water molecules and four nitrogen atoms; two N-atoms are the end atoms of azide groups and the other two nitrogen atoms belong to the 3-methylpyridine molecules. The polyhedra are linked via hydrogen bonds between the water molecules and the azide groups.     

Alkylation of tellurium tetrachloride by trimethylaluminum. Synthesis and molecular structure of [Te(CH3)3][Al(CH3)2Cl2]: A novel organotelluronium-aluminum oligomer

Reaction of TeCl₄ with A1(CH₃)₃ in toluene affords the crystalline product [Te(CH₃)₃][Al(CH₃)₂Cl₂]. The title compound crystallized in the monoclinic space group P2₁/n with unit cell parametersa=11.630(3),b=12.595(4),c=8.409(2) Å,=89.97(2)°, andD _c =1.62 g cm^–3 forZ=4. Least-squares refinement based on 1354 observed reflectionsI3 (I) in the range 3.5<2<45.0° led to a finalR factor of 0.046 (R _w =0.067). The compound does not exist as discrete cations and anions but may be described as an organotelluronium-aluminum oligomer. The mean Te-C bond distance is 2.130(11) Å while the mean Al-Cl bond distance is 2.221(4) Å.     

Crystal structure and phase transition in the compound [C6H5CH2NH(CH3)2]TlCl4

The N‐N dimethyl benzylammonium tetrachlorothallate (III) [C₆H₅CH₂NH(CH₃)₂]TlCl₄ crystallizes in the monoclinic system P2₁/n at room temperature with the following unit cell dimensions: a = 7.725(3) Å, b = 14.080(5) Å, c = 13.697(4) Å, β = 91.2(2)° with Z = 4. The structure shows a layer arrangement perpendicular to the b axis: planes of [TlCl₄]^‐ tetrahedra alternate with planes of [C₆H₅CH₂NH(CH₃)₂]⁺ cations. The cohesion of the atomic arrangement is ensured by hydrogen bonds N‐H…Cl. Differential scanning calorimetric and optical birefringence measurements reveals a phase transition at T = 339K. Raman spectroscopic study and dielectric measurements were performed to discuss the mechanism of the phase transition. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

四甲基铵三氯化镉单晶体的研究

采用溶液降温法生长了[(CH3)4N]CdCl3化合物单晶,生长参数为:生长温度45℃,降温速率0.05～01℃/d,经过30天生长,可获得尺寸为18.6mm×17.6mm×20.8mm的单晶.测定了晶体的红外光谱,X射线衍射和热分析;研究了晶体的形貌、组成和结构.[(CH3)4N]CdCl3属P63空间群,晶胞参数为a=0.9116(5),b=0.9122(3),c=0.6725(4)nm.