Crystal structure of R[UO2(CH3COO)3] (R = NH 4+ , K+, or Cs+)

The single crystal structure of NH₄[UO₂(CH₃COO)₃] (I), K[UO₂(CH₃COO)₃] (II), and Cs[UO₂(CH₃COO)₃] (III) is studied by X-ray diffraction. I and II crystallize in the tetragonal crystal system. The crystal data are as follows: a = 13.6985(3) and c = 27.5678(14) ?, V = 5173.1(3) ?³, space group I4₁/a, Z = 16, and R = 0.023 for I; a = 13.8890(5) and c = 26.0839(18) ?, V = 5031.7(4) ?³, space group I4₁/a, Z = 16, and R = 0.037 for II. Crystals III are orthorhombic, a = 18.176(2), b = 13.119(2), and c = 22.088(4) ?, V = 5267(1)?³, space group Pbca, Z = 16, and R = 0.0424. In structures I–III, the uranium-containing structural units are represented by discrete mononuclear [UO₂(CH₃COO)₃]⁻ groups, which belong to the AB ₃⁰¹ (A = UO₂²⁺, B ⁰¹=CH₃COO⁻) crystal chemical group of uranyl complexes.     

Crystal structure of M4[(UO2)2C2O4(SO4)2(NCS)2] ( M = K+, Rh+) and K4[(UO2)2C2O4(SeO4)2(NCS)2]

Three heteroacidoligand uranyl complexes M ₄[(UO₂)₂C₂O₄(SO₄)₂(NCS)₂] (M = K⁺ (I), Rb⁺ (II)) and K₄[(UO₂)₂C₂O₄(SeO₄)₂(NCS)₂] (III) have been synthesized and their crystal structure has been determined by X-ray diffraction analysis. The compounds I–III are isostructural and crystallized in the monoclinic system, sp. gr. P2₁/c, Z = 2, a = 11.5548(3) ?, b = 7.0847(1) ?, c = 13.5172(3) ?, β = 93.130(1)°, V = 1104.90(4), R = 0.015 (I); a = 11.5854(9) ?, b = 7.3841(6) ?, c = 13.9072(9) ?, β = 95.754(3)°, V = 1183.74(15), R = 0.0235 (II); a = 11.6715(3) ?, b = 7.1418(2) ?, c = 13.8546(1) ?, β = 93.539(1)°, V = 1152.66(5), R = 0.0126 (III). Basic structural units of these crystals are [(UO₂)₂C₂O₄(XO₄)₂(NCS)₂]⁴⁻ chains, which belong to the crystallochemical group A ₂ K ⁰² B ₂² M ₂¹ (A = UO₂²⁺, K ⁰² = C₂O₂₋⁴, B ² = SO₄²⁻ or SeO₄²⁻, M ¹ = NCS⁻) of uranyl complexes. Uranium-containing chains are connected into a 3D framework via a system of electrostatic interactions with potassium or rubidium cations from outer spheres. Original Russian Text ? I.V. Medrish, E.V. Peresypkina, A.V. Virovets, L.B. Serezhkina, 2008, published in Kristallografiya, 2008, Vol. 53, No. 3, pp. 495–498.     

The isomorphous substitution of 2H+ for the Cu2+ cation in the complex of bis(aminoguanidine)copper(II): Crystal structures of (Cu0.61H0.78Agu2)B12H12 and (HAgu)2B12H12

An X-ray diffraction study of the (Cu_0.61H_0.78 Agu ₂)B₁₂H₁₂ (I) mixed crystal and one of its components (HAgu)₂B₁₂H₁₂ (II) is performed at 160 K (R = 0.0312 and 0.0345, respectively). Crystals I and II are isostructural. In I, two H⁺ ions partially substitute the Cu²⁺ cation, resulting in a combination of [CuAgu ₂]²⁺ and (HAgu ₂)₂₊ cations in the structure. The cations and polyhedral B₁₂H₁₂²⁻ anions have centrosymmetric structures. A square planar environment for the Cu atom is formed by four N atoms of two Agu molecules, which close five-membered chelate cycles [Cu-N, 1.9702(13) and 2.0261(10) ?]. The distant apical vertices are occupied by H atoms of the B₁₂H₁₂²⁻ anions [Cu…H, 2.805(14) ?]. In the dimeric (HAgu ₂)²⁺ cations, the proton that substitutes for the Cu²⁺ cation forms a three-center N(1)-H…N(4),N(4)′ hydrogen bond which consists of intramolecular and an intermolecular components. In crystal II, the N(1)…N(4) and N(1)…N(4)′ distances [2.685(1) and 3.111(1) ?] are longer than in I [2.610(2) and 3.027(2) ?]. In I, the Cu…H interactions connect [CuAgu ₂]²⁺ cations and B₁₂H₁₂²⁻ anions into chains. In the cells that contain the (HAgu ₂)²⁺ dimeric cation, the chains are retained due to the secondary N-H…(B-H) interactions. Numerous weak secondary interactions between the cations and anions form three-dimensional frameworks in structures I and II.     

Crystal structure of bis[diethylenetriamine-N′-(3-propionato)-N, N′,N″,O,O′]dicopper(II) Diperchlorate, [Cu2(4-Dtmp)2](ClO4)2

A complex of copper(II) with the diethylenetriaminemonopripionate ligand [Cu₂(4-Dtmp)₂](ClO₄)₂ (I) is synthesized and characterized using X-ray diffraction. The crystals of compound I are monoclinic, a = 7.740(2) Å, b = 19.199(3) Å, c = 8.449(2) Å, β = 91.61(2)°, Z = 2, and space group P2₁/n. The structural units of crystal I are centrosymmetric dimeric cations and statistically disordered ClO ₄ ⁻ anions. In the cation, the copper atom is coordinated by three N atoms [mean Cu-N, 2.01(1) Å] and two O atoms [Cu-O, 2.134(6) Å and 1.958(7) Å] of the pentadentate bridging-chelate Dtmp ligand, which occupy vertices of the trigonal bipyramid. The binuclear cations are linked via centrosymmetric pairs of hydrogen bonds into ribbons aligned parallel to the a axis of the crystal. The ClO ₄ ⁻ anions form columns in the same direction. In the crystal, the cationic ribbons and anionic columns alternate in a chessboard fashion. __________ Translated from Kristallografiya, Vol. 50, No. 3, 2005, pp. 450–454. Original Russian Text Copyright ? 2005 by Antsyshkina, Sadikov, Poznyak, Sergienko.     

Crystal structure of britvinite [Pb7(OH)3F(BO3)2(CO3)][Mg4.5(OH)3(Si5O14)]: A new layered silicate with an original type of silicon-oxygen networks

The crystal structure of a new mineral britvinite Pb_7.1Mg_4.5(Si_4.8Al_0.2O₁₄)(BO₃)(CO₃)[(BO₃)_0.7(SiO₄)_0.3](OH, F)_6.7 from the Lángban iron-manganese skarn deposit (V?rmland, Sweden) is determined at T = 173 K using X-ray diffraction (Stoe IPDS diffractometer, λMoKα, graphite monochromator, 2θ_max = 58.43°, R = 0.052 for 6262 reflections). The main crystal data are as follows: a = 9.3409(8) ?, b = 9.3579(7) ?, c = 18.8333(14) ?, α = 80.365(6)°, β = 75.816(6)°, γ = 59.870(5)°, V = 1378.7(2) ?³, space group P1, Z = 2, and ρ_calcd = 5.42 g/cm³. The idealized structural formula of the mineral is represented as [Pb₇(OH)₃F(BO₃)₂(CO₃)][Mg_4.5(OH)₃(Si₅O₁₄)]. It is demonstrated that the mineral britvinite is a new representative of the group of mica-like layered silicates with structures in which three-layer (2: 1) “sandwiches” composed of tetrahedra and octahedra alternate with blocks of other compositions, such as oxide, oxide-carbonate, oxide-carbonate-sulfate, and other blocks. The tetrahedral networks (Si₅O₁₄)_∞∞ consisting of twelve-membered rings are fragments of the britvinite structure. Similar networks also form crystal structures of the mineral zeophyllite and the synthetic phase Rb₆Si₁₀O₂₃. In the crystal structures under consideration, the tetrahedral networks differ in the rotation of tetrahedra with respect to the layer plane. Original Russian Text ? O.V. Yakubovich, W. Massa, N.V. Chukanov, 2008, published in Kristallografiya, 2008, Vol. 53, No. 2, pp. 233–242.     

A novel representative {[Rb1.94(H2O,OH)3.84](H2O)0.1}{Al4(OH)4[PO4]3} in the pharmacosiderite structure type

The crystal structure of a new synthetic aluminophosphate {[Rb_1.94(H₂O,OH)_3.84](H₂O)_0.1}{Al₄(OH)₄[PO₄]₃} synthesized under mild hydrothermal conditions (T = 280°C, P = 100 atm) in the Rb₂O-Al₂O₃-P₂O₅-H₂O system is determined using X-ray diffraction (Stoe IPDS diffractometer, λMoK _α, graphite monochromator, 2θ_max = 64.33°, R = 0.032 for 312 reflections). The main crystal data are as follows: a = 7.4931(6) ?, space group P 3m, Z = 1, and ρ_calcd = 2.76 g/cm³. It is shown that the synthesized compound belongs to the pharmacosiderite structure type with a characteristic mixed open microporous framework composed of octahedra and tetrahedra. A comparative crystal chemical analysis of related phases is performed, and the chemical compositions of promising absorbents, i.e., hypothetical compounds potentially possible in the structure type under consideration, are proposed. It is established that pharmacosiderite and rhodizite are homeotypic to each other. Original Russian Text ? O.V. Yakubovich, W. Massa, O.V. Dimitrova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 3, pp. 442–449.     

Structure type of hexagonal tantalum bronzes with variable composition K6Ta6 + ZO15F6(F, O)y: Ta(5 ? δ)+ bronzes and Ta5+ compounds

The structure type of hexagonal compounds with the variable composition K₆Ta_{6 + z} O₁₅F₆ (F, O)_y, where Z ≤ 1 and y ≤ 3 (sp. gr. P6/m, a ∼ 13.12 Å, c ∼ 3.86 Å) has been studied. Based on the structural data for a crystal of the Ta⁵⁺-containing compound and two crystals of Ta^{(5 − δ)+}-containing bronzes formed at the cathode during electrolysis of salt melts containing Ta⁺ cations, it was established that the bronze formation is associated with the interstitial defects of intercalated Ta cations. The scheme of reduction of Ta cations at the cathode is suggested, and the formulas of the compounds are obtained with due regard for partial Ta reduction to various integral oxidation degrees. The crystals of the colorless transparent Ta⁵⁺-containing compound of the composition K₆Ta _6.27 ⁵⁺ O₁₅F_7.4, brown semitransparent partly reduced Ta⁺-containing bronze of the composition K₆Ta _6.33 ⁵⁺ Ta _0.55 ⁺ O₁₅F_8.2, and dark gray metal-like completely reduced Ta⁺-containing bronze of the composition K₆Ta ₆ ⁵⁺ Ta⁺O₁₅F₇ are studied experimentally. __________ Translated from Kristallografiya, Vol. 49, No. 1, 2004, pp. 75–91. Original Russian Text Copyright ? 2004 by Arakcheeva, Chapuis, Grinevich, Shamrai. Dedicated to the 80th Birthday of L.A. Shuvalov     

Single crystals of the fluorite nonstoichiometric phase Eu 0.9162+ Eu 0.0843+ F2.084 (conductivity, transmission, and hardness)

The nonstoichiometric phase EuF_2+x has been obtained via the partial reduction of EuF₃ by elementary Si at 900–1100°C. Eu_0.916²⁺Eu_0.084³⁺F_2.084 (EuF_2.084) single crystals have been grown from melt by the Bridgman method in a fluorinating atmosphere. These crystals belong to the CaF₂ structure type (sp. gr. Fm $ \bar 3 $ \bar 3 m) with the cubic lattice parameter a = 5.8287(2) ?, are transparent in the spectral range of 0.5–11.3 μm, and have microhardness H _μ = 3.12 ± 0.13 GPa and ionic conductivity σ = 1.4 × 10⁻⁵ S/cm at 400°C with the ion transport activation energy E _a = 1.10 ± 0.05 eV. The physicochemical characteristics of the fluorite phases in the EuF₂ − EuF₃ systems are similar to those of the phases in the SrF₂ − EuF₃ and SrF₂ − GdF₃ systems due to the similar lattice parameters of the EuF₂ and SrF₂ components. Europium difluoride supplements the list of fluorite components MF₂ (M = Ca, Sr, Ba, Cd, Pb), which are crystal matrices for nonstoichiometric (nanostructured) fluoride materials M _{1 − x} R _x F_{2 + x} (R are rare earth elements).     

Palladium (II) compounds with diaminocarboxylic acids: Crystal structures of [Pd(H2Cdta)] · H2O, [Pd(H3Edtp)Cl] · 2H2O, and (H6Edtp)[PdCl4] · 4H2O

The crystal structures of three Pd(II) compounds with diamine tetracarboxylates in different protonation states are determined, namely, [Pd(H₂ Cdta)] · H₂O (I), [Pd(H₃ EdtpCl] · 2H₂O (II), and (H₆ Edtp)[PdCl₄] · 4H₂O (III) (R ₁ = 0.0230, 0.0313, and 0.0277 for 3040, 3377, and 3809 reflections with I > 2σ(I) for I–III, respectively). Crystals I and II are built of neutral complexes [Pd(H₂ Cdta)] and [Pd(H₃ Edtp)Cl], respectively, and crystallization water molecules. Crystal III consists of [PdCl₄]²⁻ anionic complexes, H₆ Edtp ²⁺ cations, and water molecules. In I, one of the protonated acetate groups of the H₂ Cdta ²⁻ ligand forms a very weak additional Pd-O bond [2.968(2) Å] over the 2N + 2O coordination square. In II and III, the protonated propionate groups of the H₃ Edtp ⁻ ligand and the H₆ Edtp ²⁺ cation are not involved in Pd coordination and the coordination squares consist of the 2N + O + Cl and 4Cl atoms, respectively. __________ Translated from Kristallografiya, Vol. 48, No. 2, 2003, pp. 278–282. Original Russian Text Copyright ? 2003 by Polyakova, Poznyak, Sergienko.     

Crystal structure refinement of bifluorides MHF2 (M = Na, NH4, Rb). Crystal structures of Rb5F4(HF2) · 2H2O and RbF · H2O

The crystal structures of alkali metal and ammonium bifluorides MHF₂ (M = Na, NH₄, or Rb) are refined using single-crystal X-ray diffraction. In all the crystals of acid fluorides studied, HF ₂ ^t- anions have a linear structure with F⋯F distances ranging from 2.277 to 2.281 Å. The crystal structures of the Rb₅F₄(HF₂) · 2H₂O and RbF · H₂O compounds are determined. It is established that, in these structures, the O-H⋯F hydrogen bonds whose lengths are equal to 2.55–2.57 and 2.63 Å participate in the formation of trinuclear bent anions and zigzag anionic chains, respectively. __________ Translated from Kristallografiya, Vol. 50, No. 5, 2005, pp. 834–839. Original Russian Text Copyright ? 2005 by Troyanov.     

Crystal structure and hydrogen bonding of propargylammonium hexafluorosilicate, 2(C3H6N)+ (SiF6)2?

The X-ray crystal structure of propargylammonium hexafluorosilicate, 2(C₃H₆N)⁺ (SiF₆)²⁻, is determined. The SiF₆ anion is involved in N−H...F and C−H...F interactions with eight surrounding cations. This involves two-three-and four-center N−H...F hydrogen bonds, and additional C−H...F interactions with C...F distances down to 2.963(6) ?. The alkynyl C−H donors form only C−H...F interactions of unfavorable geometries.     

Synthesis and X-ray structural investigations of 2-amino-7-methyl-4-(1-naphthyl)-5-oxo4H,5H-pyrano[4,3-b]pyran-3-carbonitrile and 2-amino-4-(1-naphthyl)-5-oxo-4H,5Hpyrano[3,2-c]chromene-3-carbonitrile

Synthesis and X-ray structural investigations have been carried out for the two title compounds C₂₀H₁₄N₂O₃ (4) and C₂₃H₁₄N₂O₃⋅C₂H₃N (5). Compound 4 crystallizes in the monoclinic space group P2₁/n, with a = 7.0542(5), b = 8.822(1), c = 24.833(2) ?, β = 94.30(4)^∘, V = 1541.0(4) ?³, and Z = 4. Compound 5 crystallizes with an acetonitrile solvent molecule in the monoclinic space group P2₁/n, with a = 11.075(1), b = 7.854(1), c = 22.703(2) ?, β = 90.67(1)^∘, V = 1974.5(3) ?³, and Z = 4. In both molecules, the 4H-pyran ring adopts a flattened-boat conformation. The naphthalene substituent occupies a pseudo-axial position and the dihedral angle with the flat part of the pyran ring is equal to 94.6(3) in 4 and 76.8(3)^∘ in 5. The mutual orientation of these fragments and the flatness of the heterocyclic rings lead to H⋅sH intramolecular steric interactions: H4A⋅sH18A 1.98 ? in 4 and 2.11 ? in 5. In the crystal of 4, intermolecular hydrogen bonds N–H⋅sO and C–H⋅sN link molecules into infinite tapes along the b axis. In the crystals of 5, intermolecular hydrogen bonds N–H⋅sO and C–H⋅sN link molecules into infinite layers parallel to the bc plane. In each case, the C–H⋅sN interaction can be considered to be a weak hydrogen bond. The acetonitrile molecules link via intermolecular weak C–H⋅sN hydrogen bonds to form infinite chains along the b axes.     

General structural features of centric and acentric polymorphic pairs of organic molecular crystals: II. Polymorphic pairs P21/c-P21, P21/c-Pc, and P21/c-Pna21

A systematic investigation into the general structural features of centric and acentric polymorphic pairs of organic molecular crystals is performed using the data available in the Cambridge Structural Database. The structural aspects of the P2₁/c-P2₁, P2₁/c-Pc, and P2₁/c-Pna2₁ polymorphic pairs are considered. The most important inferences made in this study are as follows: (i) the centric and acentric modifications rather frequently (∼50% of all the cases) crystallize simultaneously under the same conditions (concomitant polymorphism); (ii) the unit cell parameters of these modifications are found to be either close in magnitude or multiples; (iii) in the centric and acentric modifications, identical or very similar types of chiral or acentric stable molecular associates are formed through hydrogen bonds or other specific intermolecular interactions; and (iv) the centric and acentric modifications more often than other compounds are characterized by polysystem unit cells (Z′ > 1). __________ Translated from Kristallografiya, Vol. 48, No. 2, 2003, pp. 293–314. Original Russian Text Copyright ? 2003 by Kuleshova, Antipin.     

Crystal and Molecular Structures of C6H5CH2SOCH2CONHCH2C6H5 and C6H5SOCH2CON(iC3H7)2

Abstract  The crystal structures for two of the ligands C₆H₅CH₂SOCH₂CONHCH₂C₆H₅ (1) and C₆H₅SOCH₂CON(ⁱC₃H₇)₂ (2) have been determined by X-ray diffraction. These compounds crystallize in orthorhombic system with space groups and cell parameters, Pca21(no. 29), a = 8.4600(5) ?, b = 5.3534(5) ?, c = 32.136(2) ?, V = 1455.42(15) ?³ and Pna21(no. 33) a = 17.5563(11) ?, b = 5.7902(4) ?, c = 14.2866(9) ?, V = 1452.30(16) ?³, respectively. These molecules are stabilized in solid state by various intra and intermolecular hydrogen bonding interactions to give polymeric structures. The reported IR spectra of these compounds in solid state could be explained on the basis of the observed intermolecular hydrogen bonding interactions. Index Abstract  The title compounds C₆H₅CH₂SOCH₂CONHCH₂C₆H₅ (1) and C₆H₅SOCH₂CON(ⁱC₃H₇)₂ (2) were prepared by the oxidation of corresponding sulfides with H₂O₂/SeO₂ in methanol and their structures were determined. The structures show that the SO and CO groups are having “anti” configuration in 1 and “syn” configuration in 2. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis, structure and supramolecular assembly in the crystalline state of a bifunctionalized arylimido derivative of hexamolybdate [n-Bu4N]2[Mo6O17(o,p-(MeO)2C6H3N)2]

A novel bifunctionalized arylimido derivative of hexamolybdate [n-Bu₄N]₂[Mo₆O₁₇(o,p-(MeO)₂C₆H₃N)₂] (1) was synthesized by self-assembled metathesis of α-type octamolybdate ion and 2,4-dimethoxyaniline and structurally characterized by crystal X-ray diffraction. Crystallographic data for1: monoclinic system, space group:C2/c,a = 17.319(4),b = 18.087(4),c = 21.357(5) ?, β = 106.486(4),V = 6415(2) ?³, andZ = 4,D_c = 1.693 g/cm³,R₁ = 0.0439. The complex has a short Mo–N bond length of 1.735(5) ? and an imido (Mo–N–C) bond angle of 177.8(4)^∘. The complex has also been characterized by¹H NMR, IR, and UV–vis spectroscopy.     

Enantiomorphism of the Ca3Ga2Ge4O14 compound and comparison of the Ca3Ga2Ge4O14 and Sr3Ga2Ge4O14 structures

The absolute crystal structures of two enantiomorphic forms of the Ca₃Ga₂Ge₄O₁₄ crystals (a = 8.075(1) ?, c = 4.9723(6) ?, space group P321) with the positive and negative senses of the optical activity are determined using X-ray diffraction analysis. The final R factors are as follows: R = 1.75% and R _w = 2.57% for the crystal with the positive sense of the optical activity and R = 1.86% and R _w = 2.78% for the crystal with the negative sense of the optical activity. The replacement of the Ca²⁺ ions by larger Sr²⁺ ions (with the formation of the Sr₃Ga₂Ge₄O₁₄ compound) leads to an anisotropic expansion of the crystal lattice (with a more considerable increase in the lattice parameter a as compared to the lattice parameter c), a change in the occupation of the 1a and 3f positions by the Ga³⁺ and Ge⁴⁺ ions, and symmetrization of the octahedra and tetrahedra forming the structural framework. The shape of the dodecahedron changes so that its size along the polar electric axis 2 increases significantly. This change is the main factor responsible for the increase in the piezoelectric activity of the Sr₃Ga₂Ge₄O₁₄ compound as compared to the piezoelectric activity of the Ca₃Ga₂Ge₄O₁₄ compound. Original Russian Text ? B.V. Mill, A.A. Klimenkova, B.A. Maximov, V.N. Molchanov, D.Yu. Pushcharovsky, 2007, published in Kristallografiya, 2007, Vol. 52, No. 5, pp. 816–823.     

Synthesis and crystal structure of Cu3(Bipy)2(L1)2(L2)2? 4H2O(Bipy = 2,2′-bipyridine, L1 =1-((2-sulfonateethylimino)methyl)-2-naphthol), L2 = 2-hydroxy-1-naphthaldehyde)

The title compound, Cu₃(Bipy)₂(L¹)₂(L²)₂⋅4H₂O, was synthesized in the methanol solution of Bipy and Cu(II) in the presence of 1-((2-sulfonate-ethylimino)-methyl)-2-naphthol (L¹), which was condensation compound of taurine and 2-hydroxy-1-naphthaldehyde. This complex crystallized in the space group P-1 with a = 9.825(2) ?, b = 12.626(2) ?, c = 14.342(3) ?, α = 90.29(1)^∘, β = 100.67(1)^∘, γ = 101.67(2)^∘, and Z = 2. In the trinuclear Cu(II) complex, there are two type Cu atoms which have square and square pyramid geometries, respectively. The Cu–N distances vary from 1.965(3) to 2.000(4) ?, while the Cu–O distances are between 1.896(3) and 2.337(4) ?.     

Interaction of copper(II) halides with 4-(piperidyl-1)-2-phenylpyrido[2,3- a ]anthraquinone-7,12 ( L ) in acidic media: Crystal structure and spectral characteristics of (H L )2[Cu2Cl6] and (H L )[CuBr2]

4-(Piperidyl-1)-2-phenylpyrido[2,3-a]anthraquinonium-7,12 hexachlorodicuprate(II) and 4-(piperidyl-1)-2-phenylpyrido[2,3-a]anthraquinonium-7,12 dibromocuprate(I) are isolated in the crystalline state and investigated using X-ray diffraction. It is established that the Cu(II) cation is reduced to the Cu(I) cation during the synthesis of anionic bromocuprate complexes in the presence of hydrobromic acid. The spectral characteristics of the prepared compounds are discussed. Original Russian Text ? O.V. Kovalchukova, A.I. Stash, S.B. Strashnova, V.K. Belsky, Tran Than Tung, B.E. Zaĭtsev, 2008, published in Kristallografiya, 2008, Vol. 53, No. 3, pp. 484–487.     

Crystal structure of the mixed-ligand copper(II) complex with S-proline-N-monoacetate dianion and imidazole [Cu(Proma)(Im)] · H2O

The crystal structure of the [Cu(Proma)(Im)] · H₂O coordination compound (where Proma ²⁻ is an S-proline-N-monoacetate dianion and Im is imidazole) is studied by X-ray diffraction. The crystals are orthorhombic, a = 8.286 Å, b = 8.546 Å, c = 17.309 Å, Z = 4, and space group P2₁2₁2₁. The structural units of the crystal are the [Cu(Proma)(Im)] molecular complexes and crystallization water molecules. The square coordination of the Cu atom involves O atoms of two acetate groups (Cu-O, 1.958 and 1.955 Å) and N atoms of the Proma and Im ligands (Cu-N, 1.986 and 1.958 Å). The terminal O atoms of the neighboring complexes complete the Cu coordination polyhedron to a 4 + 1 + 1 square bipyramid (Cu-O, 2.578 and 2.783 Å) and form a framework structure. The hydrogen bonds involving oxygen atoms of the Proma ligand, water molecules, and an uncoordinated nitrogen atom of the Im ligand contribute to the strengthening of the framework. __________ Translated from Kristallografiya, Vol. 49, No. 5, 2004, pp. 871–875. Original Russian Text Copyright ? 2004 by Antsyshkina, Sadikov, Sergienko, Poznyak.     

Refinement of the crystal structures of the La3Ta0.5Ga5.5O14 and La3Nb0.5Ga5.5O14 compounds

This paper reports on the results of accurate X-ray structural investigations of single crystals La₃Ta_0.5Ga_5.5O₁₄ (a = 8.2260(1) ?, c = 5.1207(1) ?, R/R _w = 1.09%/1.10%, 3868 unique reflections) and La₃Nb_0.5Ga_5.5O₁₄ (a = 8.2237(1) ?, c = 5.1247(1) ?, R/R _w = 1.02%/1.03%, 3735 unique reflections) (space group P321, Z = 1, sinϑ/λ|_max ≈ 1.34 ?⁻¹ for both compounds). Using sets of data with a large number of high-angle reflections makes it possible to reliably compare the crystal structures by applying statistical tests. The structural differences between the La₃Ta_0.5Ga_5.5O₁₄ and La₃Nb_0.5Ga_5.5O₁₄ crystals are weakly pronounced, which correlates with the closeness of their piezoelectric characteristics. Original Russian Text ? A.P. Dudka, B.V. Mill, Yu.V. Pisarevsky, 2009, published in Kristallografiya, 2009, Vol. 54, No. 4, pp. 599–607.