Synthesis and structure of {NH2(C2H5)2}2[(UO2)2(C2O4)(CH3COO)4] · 2H2O

Single crystals of the compound {NH₂(C₂H₅)₂}₂[(UO₂)₂C₂O₄(CH₃COO)₄] · 2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 9.210(2) ?, b = 14.321(3) ?, c = 12.659(3) ?, β = 105.465(13)°, V = 1609.2(6) ?³, space group P2₁/c, Z = 2, and R = 0.0198. The structural units of crystals I are binuclear groups of the composition [(UO₂)₂C₂O₄(CH₃COO)₄]²⁻ with an island structure, which belong to the crystal-chemical group A ₂ K ⁰² B ₄⁰¹ (A = UO₂²⁺, K ⁰² = C₂O₄²⁻, B ⁰¹ = CH₃COO⁻) of the uranyl complexes, diethylammonium cations, and water molecules. The uranium-containing groups are joined into a three-dimensional framework through electrostatic interactions with diethylammonium cations and a system of hydrogen bonds, which are formed with the participation of the atoms involved in the composition of the water molecules, oxalate ions, acetate ions, and diethylammonium cations. Original Russian Text ? L.B. Serezhkina, A.V. Vologzhanina, N.A. Neklyudova, V.N. Serezhkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 1, pp. 65–67.     

Synthesis and X-ray structural investigation of (C3N6H7)4(CN3H6)2[UO2(CrO4)4] · 4H2O and (H3O)6[UO2(CrO4)4]

Single crystals of the compounds (C₃N₆ H₇)₄(CN₃H₆)₂[UO₂(CrO₄)₄] · 4H₂O (I) and (H₃O)₆[UO₂(CrO₄)₄] (II) are synthesized, and their structures are investigated using X-ray diffraction. Compound I crystallizes in the triclinic system with the unit cell parameters a = 6.3951(8) ?, b = 10.8187(16) ?, c = 16.9709(18) ?, α = 93.674(4)°, β = 97.127(4)°, γ = 92.020(4)°, space group, P Z = 1, V = 1161.6(3) ?³, and R = 0.0470. Crystals of compound II belong to the monoclinic system with the unit cell parameters a = 14.3158(4) ?, b = 11.7477(3) ?, c = 13.1351(4) ?, β= 105.836(1)°, space group C2/c, Z = 4, V = 2125.2(1) ?³, and R = 0.0213. The uranium-containing structural units of crystals I and II are mononuclear anionic complexes of the composition [UO₂(CrO₄)₄]⁶⁻ with an island structure, which belong to the crystal-chemical group Am ₁⁴ (A = UO₂₊², M ¹ = CrO₂₋⁴) of the uranyl complexes. The [UO₂(CrO₄)₄]⁶⁻ anionic complexes are joined into a three-dimensional framework through the electrostatic interactions with outer-sphere cations and a system of hydrogen bonds. Original Russian Text ? L.B. Serezhkina, E.V. Peresypkina, A.V. Virovets, A.G. Verevkin, D.V. Pushkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 2, pp. 284–290.     

Syntheses, Characterization and Structural Determination of Nine Coordinated N2H5[Ce(edta)(H2O)3]·4H2O and N2H5[Eu(edta)(H2O)3]·4H2O

Abstract  

Hydrazinium complexes of Ce(III) and Eu(III) ethylenediaminetetra-acetate hydrates have been synthesized in aqueous solution and characterized by hydrazine and metal analyses, elemental analysis, infrared spectra, X-ray power diffraction and single crystal X-ray diffraction techniques. The Ce^IIIN₂O₇ parts in the complex anion has a pseudomono-capped square antiprismatic nine-coordinate structure, in which the six coordinated atoms (two N and four O) from the ethylenediaminetetraacetate ion and three water molecules are coordinated to the central rare earth metal ion directly. The Eu^IIIN₂O₇ part in the complex anion has the same structure as Ce^IIIN₂O₇ part. The crystal of the cerium complex belongs to the orthorhombic crystal system and Fdd2 space group. The crystal data are the follows: a = 19.7281(7) ?, b = 35.7790(11) ?, c = 12.3244(4) ?, α = β =γ = 90^°, V = 8699.2(5) ?³. The final R and Rw are 0.020 and 0.0589 for with I > 2σ (I) and 3,842 reflections, respectively. The crystal of the europium complex is isostructural with the cerium complex. The crystal data of europium complex are: a = 19.7281(7) ?, b = 35.7790(11) ?, c = 12.3244(4) ?, α = β =γ = 90^°, V = 8699.2(5) ?³. The final R and Rw are 0.0252 and 0.687 for with I > 2σ (I) and 3,842 reflections, respectively. The X-ray powder diffraction patterns and infrared spectra of the complex are super imposable indicating their structural similarity.     

Synthesis and X-ray structural investigation of K8[(UO2)2(C2O4)2(SeO4)4] · 2H2O

Single crystals of the compound K₈[(UO₂)₂(C₂O₄)₂(SeO₄)4] · 2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Compound I crystallizes in the monoclinic system with the unit cell parameters a = 14.9290(4) ?, b = 7.2800(2) ?, c = 15.3165(4) ?, β = 109.188(1)°, V = 1572.17(7) ?³, space group P2₁/n, Z = 2, and R = 0.0297. The uranium-containing structural units of crystals I are dimers of the composition [(UO ₂)₂(C₂O₄)₂(SeO₄)₄]⁸⁻, which belong to the crystal-chemical group AB ⁰¹ B ² M ¹ (A = UO₂²⁺, B ⁰¹ = C₂O₄²⁻, B ² = SeO₄²⁻, M ¹ = SeO₄²⁻) of the uranyl complexes. The [(UO₂)₂(C₂O₄)₂(SeO₄)₄]⁸⁻ dimers are joined into a three-dimensional framework through electrostatic interactions with the outer-sphere potassium cations. Original Russian Text ? L.B. Serezhkina, E.V. Peresypkina, A.V. Virovets, A.G. Verevkin, D.V. Pushkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 1, pp. 68–71.     

X-ray diffraction study of R2[UO2(C3H2O4)2] ·H2O (R = K or Rb)

Compounds K₂[UO₂(C₃H₂O₄)₂] · H₂O (I) and Rb₂[UO₂(C₃H₂O₄)₂] · H₂O (II) are synthesized and their crystal structures are determined by X-ray diffraction. The compounds crystallize in the monoclinic crystal system; for I, a = 7.1700(2) ?, b =12.3061(3) ?, c = 14.3080(4) ?, β = 95.831(2)°, space group P2₁/n, Z = 4, and R = 0.0275; for II, a = 7.1197(2) ?, b = 12.6433(4) ?, c = 14.6729(6) ?, β = 96.353(2)°, space group P2₁/n, Z = 4, and R = 0.0328. It is found that I and II are isostructural. The main structural units of the crystals are the [UO₂(C₃H₂O₄)₂]²⁻ chains, which belong to the AT ¹¹ B ⁰¹ (A = UO₂²⁺, T ¹¹, and B ⁰¹ = C₃H₂O₄²⁻) crystal chemical group of uranyl complexes. The chains and alkali metal ions R (R = K or Rb) are connected by electrostatic interactions and hydrogen bonds. Some specific structural features of [UO₂(C₃H₂O4)₂]²⁻ complex groups are discussed.     

Synthesis and structure of K2[(UO2)4(O)2(OH)2(C2O4)(CH3COO)2(H2O)2]·2H2O

Single crystals of the compound K₂[(UO₂)₄(O)₂(OH)₂(C₂O₄)(CH₃COO)₂(H₂O)₂]·2H₂O (I) are synthesized, and their structure is investigated using X-ray diffraction. Crystals of compound I belong to the triclinic system with the unit cell parameters a = 7.6777(6) ?, b = 7.9149(7) ?, c = 10.8729(9) ?, α = 72.379(2)°, β = 86.430(3)°, γ = 87.635(2)°, V = 628.33(9) ?³, space group P , Z = 1, and R ₁ = 0.0323. The main structural units of the crystals are [(UO₂)₄(O)₂(OH)₂(C₂O₄)(CH₃COO)₂(H₂O)₂]²⁻ chains, which belong to the crystal-chemical group A ₄ M ₂³ M ₂² K ⁰² B ₂⁰¹ M ₂¹ (A = UO₂²⁺, M ³ = O²⁻, M ² = OH⁻, K ⁰² = C₂O₄²⁻, B ⁰¹ = CH₃COO⁻, M ¹ = H₂O) of the uranyl complexes. The chains are formed by linking the centrosymmetric tetramers of the composition (UO₂)₄(O)₂(OH)₂(CH₃COO)₂(H₂O)₂ via tetradentate bridging oxalate ions. The uranium-containing groups are joined into a three-dimensional framework through the electrostatic interaction with potassium cations and a system of hydrogen bonds, which are formed with the participation of atoms involved in the composition of the water molecules, hydroxide ions, and uranyl ions. Original Russian Text ? L.B. Serezhkina, A.V. Vologzhanina, N.A. Neklyudova, V.N. Serezhkin, 2009, published in Kristallografiya, 2009, Vol. 54, No. 3, pp. 483–487.     

Structural Studies of the Coupling Products Between (C6H5)CH=NR (R?=?C6H5, i-C3H7) and the Ti(C5H5)(2,4-C7H11) Fragment (C7H11?=?dimethylpentadienyl)

Abstract  

The reactions of imines of the formula (C₆H₅)CH=NR (R = C₆H₅, i-C₃H₇) with Ti(C₅H₅)(2,4-C₇H₁₁)(PMe₃) (C₇H₁₁ = dimethylpentadienyl) lead to expulsion of the PMe₃ and coupling between the imine’s carbon atom and a single terminus of the 2,4-C₇H₁₁ ligand, resulting in C₅H₅, “diene,” and π-amide coordination in the 16 electron products. Examination of the Ti–C and C–C bonding parameters for the “diene” ligands reveals that they may be more appropriately regarded as enediyl ligands, leading to a formal +4 oxidation state for titanium. Both complexes crystallize in the triclinic space group P[`1] P\overline{1} . For the R = C₆H₅ coupling product, a = 10.4590(2) ?, b = 11.6407(2) ?, c = 17.3729(3) ?, α = 74.7610(7)°, β = 79.8600(6)°, γ = 82.2895(11)°, V = 2000.28(6) ?³, D _calc = 1.293 g/cm³ at 150(1) K. For the R = i-C₃H₇ coupling product, a = 8.1039(2) ?, b = 9.4115(2) ?, c = 13.0116(4) ?, α = 88.9906(18)°, β = 73.2780(15)°, γ = 83.3088(16)°, V = 943.82(4) ?³, D _calc = 1.250 g/cm³ at 150(1) K.     

Crystal and molecular structure of Sr2( Edta ) · 5H2O, Sr2(H2 Edta )(HCO3)2 · 4H2O, and Sr2(H2 Edta )Cl2 · 5H2O strontium ethylenediaminetetraacetates

Three Sr²⁺ compounds with the Edta ⁴⁻ and H₂ Edta ²⁻ ligands—Sr₂(Edta) · 5H₂O (I), Sr₂(H₂ Edta)(HCO₃)₂ · 4H₂O (II), and Sr₂(H₂ Edta)Cl₂ · 5H₂O (III)—are synthesized, and their crystal structures are studied. In I, the Sr(1) atom is coordinated by the hexadentate Edta ⁴⁻ ligand following the 2N + 4O pattern and by two O atoms of the neighboring ligands, which affords the formation of zigzag chains. The Sr(2) atom forms bonds with O atoms of five water molecules and attaches itself to a chain via bonds with three O atoms of the Edta ⁴⁻ ligands. The Sr(1)-O and Sr(2)-O bond lengths fall in the ranges 2.520(2)–2.656(3) and 2.527(3)–2.683(2) ?, respectively. The Sr(1)-N bonds are 2.702(3) and 2.743(3) ? long. In II and III, the H₂ Edta ²⁻ anions have a centrosymmetric structure with the trans configuration of the planar ethylenediamine fragment. The N atoms are blocked by acid protons. In II, the environment of the Sr atom is formed by six O atoms of three H₂ Edta ligands, two O atoms of water molecules, and an O atom of the bicarbonate ion, which is disordered over two positions. In III, the environment of the Sr atom includes six O atoms of four H₂ Edta ²⁻ ligands and three O atoms of water molecules. The coordination number of the Sr atoms is equal to 8 + 1. In II and III, the main bonds fall in the ranges 2.534(3)–2.732(2) and 2.482(2)–2.746(3) ?, whereas the ninth bond is elongated to 2.937(3) and 3.055(3) ?, respectively. In II, all the structural elements are linked into wavy layers. The O-H…O interactions contribute to the stabilization of the layer and link neighboring layers. In III, hydrated Sr²⁺ cations and H₂ Edta ^– anions form a three-dimensional [Sr₂(H₂ Edta)(H₂O)₃] _n ²ⁿ⁺ framework. The Cl⁻ anions are fixed in channels of the framework by hydrogen bonds with four water molecules. In II and III, the N-H groups form four-center N-H…O₃ hydrogen bonds, which include one intermolecular and two intramolecular components. PACS numbers: 61.66.Hq Original Russian Text ? I.N. Polyakova, A.L. Poznyak, V.S. Sergienko, 2009, published in Kristallografiya, 2009, Vol. 54, No. 2, pp. 262–267.     

Structure, thermal, and infrared analyses of [NH3(CH2)3NH3]2[Ni(HP2O7)2(H2O)2] ? 4H2O

[NH₃(CH₂)₃NH₃]₂[Ni(HP₂O₇)₂(H₂O)₂] 4H₂O (NiDAP) is a new diphosphate of transition metallic and organic cations obtained from a mixture of H₄P₂O₇, 2NiCO₃ Ni(OH)₂ 4H₂O and NH₂(CH₂)₃NH₂ in a 1:1/6:1 molar ratio. This mixed organo-mineral compound crystallizes in the triclinic system, P¯, with the unit cell dimensions: a = 7.3678(3)~Å, b = 7.8018(5)Å, c = 11.1958(7)Å, = 76.914(4), = 81.052(4), = 85.46(1), V = 618.57(6)ų and Z = 1. The crystal structure of NiDAP consists of a complex anion, [Ni(HP₂O₇)₂(H₂O)₂]^4– and a diammoniumpropane cation. The complex anion is built up from two neutral water molecules (OW1) and two diphosphosphoric anions coordinated to Ni(II) in a bidentate chelating manner. (OW1) molecules link anionic complexes, [Ni(HP₂O₇)₂(H₂O)₂]^4– to create a thick bidimensional layers parallel to the (a, b) plane. These layers are interconnected in three dimensions through hydrogen bonds established between organic cations, the remaining water molecules OW2, OW3, and some external oxygen atoms of the anionic complex arrays. NiDAP was also characterized by IR spectroscopy, TG-DTA, and DSC analyses.     

Copper(I) Hexafluorosilicate π-Complex with N-Allylmorpholinium Cation: A Rare Case of (C=C?+?3O) Copper(I) Coordination in the Structure of [Cu(C4H8ONH(C3H5))(H2O)2]SiF6·H2O

Abstract  

The [Cu(C₄H₈ONH(C₃H₅))(H₂O)₂]SiF₆·H₂O compound (I) was obtained by alternating current electrochemical synthesis, starting from a solution containing CuSiF₆·4H₂O and N-allylmorpholinium hexafluorosilicate. Compound I crystallizes in a trigonal P 3₁ space group, a = 8.6449(4), c = 16.5629(11) Å, V = 1071.98(10) ų, Z = 3 for Cu(C₇H₁₄NO)SiF₆·3H₂O composition, R = 0.0569 for 2987 reflections and 182 refined parameters. The C=C bond of one N-allylmorpholinium cation, elongated to 1.38(1) Å, the O-atom from another ligand moiety, and two oxygen atoms from two water molecules form the trigonal-pyramidal environment of the metal atom. The bridging function of the ligand moiety results in infinite metal-organic chains. One more water molecule is fixed in the crystal space by hydrogen bonds only.     

Preparation and Characterization of [Zn(H2O)6][Zn2V10O28(H2O)10]?·?6H2O Single Crystals with a Novel Metallic Heteropolyoxoanion

Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra. The Zn(1)O₆ octahedron and three water molecules associated with it are located between the different layers. The [Zn(H₂O)₆][Zn₂V₁₀O₂₈(H₂O)₁₀] · 6H₂O compound belongs to P-1 space group, with a = 8.967(2) ?, b = 10.390(4) ?, c = 12.338(13) ?, α = 108.31(7)°, β = 100.68(7)°, γ = 103.00(3)°, V = 1022(1) ?³ and Z = 1. Refinement gave R = 0.035 and wR(F²) = 0.098 for 3837 unique observed reflexions [I > 2σ(I)]. Index Abstract  The compound investigated in this study contains a novel centrosymmetric heteroanion [Zn₂V₁₀O₂₈(H₂O)₁₀]²⁻. This cluster results from the connection between a V₁₀O₂₈ group and two Zn(2)O(OH₂)₅ octahedra.      

Synthesis and Crystal Structure of a New Mixed Alkali Oxalate A1?x(NH4)x(H2C2O4)(HC2O4)(H2O)2 with A?=?K, Rb

Abstract  

In the present study we report the synthesis, crystal structure, spectroscopic and thermal analysis of mixed alkali A_1−x (NH₄) _x (H₂C₂O₄)(HC₂O₄)(H₂O)₂ with A = K, Rb. Single crystal refinements showed that the two compounds Rb_0.86(NH₄)_0.14(H₂C₂O₄)(HC₂O₄)(H₂O)₂ and K_0.53(NH₄)_0.47(H₂C₂O₄)(HC₂O₄)(H₂O)₂ adopt P − 1 space group. The nine fold coordination cationic sites are randomly occupied by Rb⁺/NH₄ ⁺ and K⁺/NH₄ ⁺ respectively for rubidium and potassium compounds. The structure consists of a three-dimensional network formed by the succession along (c) axis of corrugated sheets formed by alkali polyhedra layers in the packing of four-membered rings [A₄(HC₂O₄)₂(H₂C₂O₄)₂] linked and bridged by oxalate groups that behave as bi and tetradentate ligand under three different coordination modes. The stability of the crystal lattice is ensured by interesting hydrogen bonding contacts: N–H···O and O–H···O. The thermal behavior under air reveals two anomalies at 368 and 402 K attributed respectively to a structural phase transition probably due to the reorientation of ammonium tetrahedral and to the release of crystalline water. IR spectroscopy further confirms that this material loses crystallization water gradually in the temperature range 400–460 K.     

X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C2H5O-C6H4-CH=N-C6H4-CH3 and C4H9O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-alkoxybenzylidene)-p′-toluidines C₂H₅O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₄H₉O-C₆H₄-CH=N-C₆H₄-CH₃ (2) are determined by X-ray diffraction. Crystals 1 and 2 contain four and two crystallographically independent molecules, respectively. In 1, the geometry of the independent molecules is almost identical. In 2, the independent molecules differ in the conformation of the alkyl chain, which is disordered in one of them. An analysis of the crystal packing of 2 reveals the alternation of spacious layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments, which ensures the formation of the mesogenic phase in the course of melting of crystals 2. In crystal 1, loose aliphatic layers are absent. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1072–1078.     

Crystal Structures and Thermal Properties of Two Transition-Metal Compounds {[Ni(DNI)2(H2O)3][Ni(DNI)2 (H2O)4]}·6H2O and Pb(DNI)2(H2O)4 (DNI?=?2,4-Dinitroimidazolate)

Abstract  

Two transition-metal compounds derived from 2,4-dinitroimidazole, {[Ni(DNI)₂(H₂O)₃][Ni(DNI)₂(H₂O)₄]}·6H₂O, 1, and Pb(DNI)₂(H₂O)₄, 2, were characterized by elemental analysis, FT-IR, TG-DSC and X-ray single-crystal diffraction analysis. Crystal data for 1: monoclinic, space group C2/c, a = 26.826(3), b = 7.7199(10), c = 18.579(2) ?, β = 111.241(2)° and Z = 4; 2: monoclinic, space group C2/c, a = 6.5347(6), b = 17.1727(17), c = 14.1011(14) ?, β = 97.7248(10) and Z = 4. Compound 1 contains two isolated nickel centers in its structure, one being six-coordinate and another five-coordinate. The structure of 2 contains a lead (II) center surrounded by two chelating DNI ligands and four water molecules in distorted square-antiprism geometry. The abundant hydrogen bonds in two compounds link the molecules into three-dimensional network and stabilize the molecules. The TG-DSC analysis reveals that the first step is the loss of water molecules and the final residue is the corresponding metal oxides and carbon.     

配位聚合物{[Mn（H2BCPBA）2（H2O）4]}n的合成和表征

采用3,5-bi(4-carboxy-phenoxy)-benzoic acid(H3BCPBA)为配体,以Mn为中心离子采用自组装的方法合成了配位聚合物{[Mn(H2BCPBA)2(H2O)4]}n,采用单晶衍射仪,红外光谱,热重,固体紫外和元素分析对其进行了晶体结构的解析和表征。它属于三斜晶系,P1空间群,晶胞参数分别为a=0.58423(13)nm,b=1.3644(3)nm,c=1.3910(3)nm,α=109.173(2)°,β=98.927(3)°,γ=99.123(3)°,V=1.0082(4)nm,Mr=913.63,Z=1,Dc=1.505 g/cm3,μ=0.414 mm-1,F(000)=471.0。热重分析表明,该配合物在410℃下稳定,UV固体光谱表明,该配合物有很弱的吸收。     

A study of the mechanisms of defect formation in K2Ni(SO4)2 · 6H2O/K2Co(SO4)2 · 6H2O bicrystals grown from aqueous solutions

The K₂Co(SO₄)₂ · 6H₂O-K₂Ni(SO₄)₂ · 6H₂O system has been studied, and a series of K₂Ni(SO₄)₂ · 6H₂O/K₂Co(SO₄)₂ · 6H₂O bicrystals have been grown. The processes of defect formation at the substrate/layer interface K₂Co(SO₄)₂ · 6H₂O/K₂Ni(SO₄)₂ · 6H₂O are studied by probe microanalysis, X-ray topography, and optical microscopy. It is found that inclusions and threading dislocations are formed at the interface, due to which elastic stresses relax in the crystal. Nickel is nonuniformly distributed in the layer; its concentration decreases with an increase in the layer thickness, which is indicative of substrate dissolution in the initial stage of interaction. A way for the elastic mismatch stresses to relax in heterostructures of brittle crystals obtained from solutions at low temperatures is proposed which implies the formation of inclusions at the substrate/layer interface. Original Russian Text ? M.S. Grigor’eva, A.é. Voloshin, E.B. Rudneva, V.L. Manomenova, S.N. Khakhanov, V.Ya. Shklover, 2009, published in Kristallografiya, 2009, Vol. 54, No. 4, pp. 679–687.     

Crystal Structures of Two Aromatic Zinc(II) Carboxylates: [Zn(4-Chlorosalicylato)2(H2O)4]·2theophylline·(H2O)2 and Unique [Zn(5-Chlorosalicylato)2(isonicotinamide)2(H2O)]

Abstract  

The crystal structures of two zinc(II) 4-chloro- and 5-chlorosalicylate complexes, [Zn(4-ClC₆H₃-2-(OH)COO)₂(H₂O)₄]·2tph·(H₂O)₂ (I) and [Zn(5-ClC₆H₃-2-(OH)COO)₂(ina)₂(H₂O)] (II), where tph is theophylline and ina is isonicotinamide, have been determined using X-ray diffraction methods. Crystals of both (I) and (II) are triclinic, space group P-1, with Z = 1 in a cell with a = 7.2220(3), b = 8.59700(10), c = 16.0210(5) ?, α = 75.990(2), β = 83.959(2), γ = 68.455(2)°, V = 897.54(5) ?³ (I) and with Z = 2 in a cell with a = 11.4148(11), b = 11.5327(10), c = 12.0685(13) ?, α = 63.458(6), β = 87.547(8), γ = 89.387(7)°, V = 1419.9(2) ?³ (II). The coordination environment of the zinc(II) atom of compound (I) consists of two unidentate carboxylate oxygen atoms and four oxygen atoms of aqua ligands, forming a distorted octahedral configuration. Two theophylline molecules and the remaining water molecules are bound only by hydrogen bonds. The Zn atom of compound (II) is pentacoordinated with two unidentate carboxylate oxygen atoms, two pyridine nitrogen atoms of isonicotinamide ligands, and the oxygen atom of the aqua ligand, forming a distorted configuration between square pyramid and trigonal bipyramid. In both complexes intramolecular O–H···O hydrogen-bonding interactions are present. In the crystal structures, molecules are linked by intermolecular O–H···O and N–H···O hydrogen bonds. The structures are analyzed and compared to the similar Zn(II) complexes, with the chromophores ZnO₆ and ZnO₃N₂.     

X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C5H11O-C6H4-CH=N-C6H4-CH3 and C8H17O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-(alkoxybenzylidene)-p′-toluidines C₅H₁₁O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₈H₁₇O-C₆H₄-CH=N-C₆H₄-CH₃ (2), which form the nematic phase upon melting, is determined by X-ray diffraction. The geometry of the benzylideneaniline fragments in molecules 1 and 2 is actually identical. The crystal packings of 1 and 2 are characterized by the alternation of layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments. The packing in the aromatic regions of 1 follows the parquet pattern. The crystal packing of 2 has a stacking structure, which is formed by π-stacking dimers superimposed on one another. The formation of the mesogenic phase upon melting of crystals 1 is due to the disturbance of the structurality of loose aliphatic layers with retention of the structure of the aromatic regions, which are stabilized by the cooperative effect of weak directed C-H ··· π-system interactions. The mesogenic phase of crystals 2 is formed upon melting as a consequence of the retention of the structure of π-stacking dimers. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1079–1085.     

Structures and Non-linear Optical Properties of Multi-Sulfur π-Conjugated Compounds 4,5-Vinylenedithio-1,3-dithiole-2-thione (C5H2S5) and 4,5-Vinylenedithio-1,3-dithiole-2-one (C5H2OS4)

Abstract Both the title multi-sulfur molecules C₅H₂S₅ (1) and C₅H₂OS₄ (2) have a chair conformation, while molecule 1 has a higher degree of π-conjugation. Both the crystals are characterized by short S···S intermolecular contacts and by face-to-face column-like packing style, but crystal 1 has been more stabilized which may be the result of its stronger π–π intermolecular interactions. Compound 1 crystallizes in non-centrosymmetric polar space group Pmn2₁ with a = 10.6826(17), b = 9.3633(11), c = 4.0764(6) ?, V = 407.74(10) ?³, and Z = 2. The molecular dipole moment of 1 is ±62.5(1)° away from the macro-polarization direction along the c-axis. Consequently, the crystalline powder of crystal 1 exhibit a second harmonic generating (SHG) intensity 0.5 time strong as that of urea standard powder crystals when irradiated by a 1,080 nm of Nd:YAP laser beam. Compound 2 shows no SHG effect because it crystallizes in centrosymmtric space group Pbca with a = 11.4208(8), b = 7.8843(9), c = 33.587(3) ?, V = 3024.3(5) ?³, and Z = 16. Index Abstract Structures and Non-linear Optical Properties of Multi-Sulfur π-Conjugated Compounds 4,5-Vinylenedithio-1,3-dithiole-2-thione (C₅H₂S₅) and 4,5-Vinylenedithio-1,3-dithiole-2-one (C₅H₂OS₄) Gang Xue, Qi Fang,* Wen-Tao Yu, Xia Chen, and Hong Lei Compound C₅H₂S₅ crystallizes in the polar space group Pmn2₁ and its crystalline powder exhibits a second harmonic generating (SHG) intensity 0.5 times that of urea standard (1080 nm → 540 nm), while the similar compound C₅H₂OS₄ has no SHG effect because of its centrosymmetric space group Pbca.      

Infrared transmission of (R2O OR R’O)–(TiO2, Nb2O5 OR Ta2O5)-Al2O3 glasses

The new families of aluminate glasses obtained by the present authors from their melts in the systems K₂O–Ta₂O₅–Al₂O₃, Na₂O–K₂O–Ta₂O₅–Al₂O₃, K₂O –Cs₂O– Ta₂O₅–Al₂O₃, K₂O–Nb₂O₅–Al₂O₃, Na₂Oz.sbnd;K₂O–TiO₂–Al₂O₃, BaO–TiO₂–Al₂O₃, BaO–ZrO₂–TiO₂–Al₂O₃ and Na₂O–K₂O–BaO–ZrO₂–Ta₂O₅–TiO₂ –Al₂O₃ showed high transmissions of visible and infrared (IR) radiation ranging from 0.4 to about 6 μm, as well as high refractive indices up to 2.0. Their physical and chemical properties such as glass-forming ability, softening temperature, hardness and hygroscopicity were comparable to conventional silicate glasses. These properties are useful for IR applications. The cause of the high IR transmission of the aluminate glasses was interpreted in terms of the masses of the constituent cations and the single bond strengths of the cations with oxygen ions.