- Hydrothermal and structural chemistry of the zinc(II)- and cadmium(II)-1,2,4-triazolate systems
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Hydrothermal reactions of 1,2,4-triazole with zinc and cadmium salts have yielded 10 structurally unique materials of the M(II)/trz/Xn- system, with M(II) = Zn and Cd and Xn- = F-, Cl-, Br-, I-, OH-, NO3-, and SO42- (trz = 1,2,4-triazolate). Of the zinc-containing phases, [Zn(trz)2] (1), [Zn2(trz)3(OH)] ·3H2O (3·3H2O), and [Zn2(trz) (SO4)(OH)] (4) are three-dimensional, while [Zn(trz)Br] (2) is two-dimensional. All six cadmium phases, [Cd3(trz)3F 2(H2O)]·2.75H2O (5·2.75H 2O), [Cd2(trz)2Cl2(H2O)] (6), [Cd3(trz)3Br3] (7), [Cd 2(trz)3I] (8), [Cd3(trz)5(NO 3)(H2O)]·H2O (9·H2O), and [Cd8(trz)4(OH)2(SO4) 5(H2O)] (10), are three-dimensional. In all cases, the anionic components Xn- participate in the framework connectivity as bridging ligands. The structural diversity of these materials is reflected in the variety of coordination poiyhedra displayed by the metal sites: tetrahedral; trigonal bipyramidal; octahedral. Structures 3, 5, and 7-9 exhibit two distinct polyhedral building blocks. The materials are also characterized by a range of substructural components, including trinuclear and tetranuclear clusters, adamantoid cages, chains, layers, and complex frameworks.
- Ouellette, Wayne,Hudson, Bruce S.,Zubieta, Jon
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- SMARTER crystallography of the fluorinated inorganic-organic compound Zn3Al2F12·[HAmTAZ]6
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We present in this paper the structure resolution of a fluorinated inorganic-organic compound - Zn3Al2F12· [HAmTAZ]6 - by SMARTER crystallography, i.e. by combining powder X-ray diffraction crystallography, NMR crystallography and chemical modelling of crystal (structure optimization and NMR parameter calculations). Such an approach is of particular interest for this class of fluorinated inorganic-organic compound materials since all the atoms have NMR accessible isotopes (1H, 13C, 15N, 19F, 27Al, 67Zn). In Zn3Al2F 12·[HAmTAZ]6, 27Al and high-field 19F and 67Zn NMR give access to the inorganic framework while 1H, 13C and 15N NMR yield insights into the organic linkers. From these NMR experiments, parts of the integrant unit are determined and used as input data for the search of a structural model from the powder diffraction data. The optimization of the atomic positions and the calculations of NMR parameters (27Al and 67Zn quadrupolar parameters and 19F, 1H, 13C and 15N isotropic chemical shifts) are then performed using a density functional theory (DFT) based code. The good agreement between experimental and DFT-calculated NMR parameters validates the proposed optimized structure. The example of Zn 3Al2F12·[HAmTAZ]6 shows that structural models can be obtained in fluorinated hybrids by SMARTER crystallography on a polycrystalline powder with an accuracy similar to those obtained from single-crystal X-ray diffraction data.
- Martineau, Charlotte,Cadiau, Amandine,Bouchevreau, Boris,Senker, Juergen,Taulelle, Francis,Adil, Karim
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- Solvent effect on 3D topology of hybrid fluorides: Synthesis, structure and luminescent properties of Zn(II) coordination compounds
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The mixture ZnF2/HFaq./Hamtetraz (Hamtetraz = 5-aminotetrazole) with the molar ratio 10/80/10 reacts at 160 °C in different solvents (methanol/water and water respectively) to give two new 3D compounds: (Zn4F4(a
- Pimenta, Vanessa,Oger, Marine,Salek, Guillaume,Hemon-Ribaud, Annie,Leblanc, Marc,Dujardin, Gilles,Maisonneuve, Vincent,Lhoste, Jér?me
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- Metal cyanide ions Mx(CN)y]+,- in the gas phase: M = Fe, Co, Ni, Zn, Cd, Hg, Fe + Ag, Co + Ag
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The generation of metal cyanide ions in the gas phase by laser ablation of M(CN)2 (M = Co, Ni, Zn, Cd, Hg), FeIII[FeIII(CN)6]·xH2O, Ag3[M(CN)6] (M = Fe, Co), and Ag2[F
- Dance, Ian G.,Dean, Philip A. W.,Fisher, Keith J.,Harris, Hugh H.
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- Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent
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A solid solution of GaN and ZnO (GaN:ZnO) is promising as a photocatalyst for visible-light-driven overall water splitting to produce H2. However, several obstacles still exist in the conventional preparation procedure of GaN:ZnO. For example, the atomic distributions of Zn and Ga are nonuniform in GaN:ZnO when a mixture of the metal oxides, i.e. Ga2O3 and ZnO, is used as a precursor. In addition, GaN:ZnO is generally prepared under a harmful NH3 flow for long durations at high temperatures. Here, a facile synthesis of GaN:ZnO with homogeneous atomic composition via a simple and safe procedure is reported. A layered double hydroxide (LDH) containing Zn2+ and Ga3+ was used to increase the uniformity of the atomic distributions of Zn and Ga in GaN:ZnO. We employed urea as a nitriding agent instead of gaseous NH3 to increase the safety of the reaction. Through the optimization of reaction conditions such as heat treatment temperature and content of urea, single-phase GaN:ZnO was successfully obtained. In addition, the nitridation mechanism using urea was investigated in detail. NH3 released from the thermal decomposition of urea did not directly nitride the LDH precursor. X-ray absorption and infrared spectroscopies revealed that Zn(CN2)-like intermediate species were generated at the middle temperature range and Ga-N bonds formed at high temperature along with dissociation of CO and CO2.
- Katagiri, Kiyofumi,Hayashi, Yuki,Yoshiyuki, Risa,Inumaru, Kei,Uchiyama, Tomoki,Nagata, Noriyuki,Uchimoto, Yoshiharu,Miyoshi, Akinobu,Maeda, Kazuhiko
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- Effect of the synthesis temperature on the dimensionality of hybrid fluorozincates
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A series of new hybrid fluorozincates incorporating 5-aminotetrazole (Hamtetraz) is obtained from a same starting mixture of ZnF2, HF solution and Hamtetraz in acetronitrile at different synthesis temperatures. The structures, determined by single crystal X-ray diffraction, exhibit various networks with dimensionalities that increase as a function of the synthesis temperature. At 120?°C, two phases, ZnF2(H2O)(Hamtetraz) (1) and ZnF2(Hamtetraz)2(2), coexist and display 1D infinite chains.∞[ZnN2F2O] chains are built up from ZnN2F3(H2O) octahedra linked by opposite fluorine corners in 1, while∞[ZnN2F2] chains of edge sharing ZnN2F4octahedra are found in 2. At 130?°C, dense layers appear in Zn3F5(H2O)2(amtetraz) (3); they result from the condensation of∞[ZnF3N2] and∞[ZnF2NO] chains by fluorine corners to form a neutral 2D network. At 140?°C, [NH4]·(Zn4F5(amtetraz)4)·3H2O (4) presents an anionic 3D network containing small cavities in which water molecules and ammonium cations are inserted. The thermal behavior of the coordination polymers 3 and 4 is studied by TGA analysis and X-ray thermodiffraction; an intermediate phase is observed during the decomposition of 4.
- Pimenta, Vanessa,Le, Quang Hoang Hanh,Hemon-Ribaud, Annie,Leblanc, Marc,Maisonneuve, Vincent,Lhoste, Jér?me
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- Direct observation of a transverse vibrational mechanism for negative thermal expansion in Zn(CN)2: An atomic pair distribution function analysis
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The instantaneous structure of the cyanide-bridged negative thermal expansion (NTE) material Zn(CN)2 has been probed using atomic pair distribution function (PDF) analysis of high energy X-ray scattering data (100-400 K). The temperature dependence of the atomic separations extracted from the PDFs indicates an increase of the average transverse displacement of the cyanide bridge from the line connecting the ZnII centers with increasing temperature. This allows the contraction of non-nearest-neighbor Zn-Zn′ and Zn-C/N distances despite the observed expansion of the individual direct Zn-C/N and C-N bonds. Thus, this analysis provides definitive structural confirmation that an increase in the average displacement of bridging atoms is the origin of the NTE behavior. The lattice parameters reveal a slight reduction in the NTE behavior at high temperature from a minimum coefficient of thermal expansion (α = dl/ldJ) of -19.8 × 10-6 K -1 below 180 K, which is attributed to interaction between the doubly interpenetrated frameworks that comprise the structure.
- Chapman, Karena W.,Chupas, Peter J.,Kepert, Cameron J.
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- Metal pyrazolato complexes. Synthesis, characterization, and X-ray powder diffraction studies of group 12 coordination polymers
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A number of polymeric pyrazolato complexes have been prepared and characterized by spectroscopy, thermal analyses (DSC and TGA), and X-ray powder diffraction (XRPD) methods. Ab initio XRPD studies showed that the (isomorphous) [Zn(pz)2]n and [Cd(pz)2]n species (Hpz = pyrazole) are 1-D polymers containing tetrahedrally coordinated metals and M(μ-pz)2M (M = Zn, Cd) bridges, much alike [Cu(pz)2]n [orthorhombic, Ibam, a = 7.4829(4), b = 14.3844(6), c =_7.3831(3) A? (Zn) and a = 7.8591(6), b = 13.652(1), c = 7.9165(4) A? (Cd)]; differently, Hg(pz)2 [triclinic, P1?, a = 7.4097(3), b = 9.4474(3), c = 5.8345(3) A, a = 96.310(2), β= 96.752(3), and γ = 73.694(2)°] is best described as a mononuclear complex, containing two monodentate pyrazolato ligands loosely interacting, through long(er) Hg?N contacts with neighboring molecules. During the synthesis of the latter, an intermediate phase was obtained, and characterized as Hg(pz)NO3, which contains a polymeric polycation, [Hg(pz)]nn+, based on Hg(μ-pz)Hg bridges, and uncoordinated NO3- groups (orthorhombic, Pcmn, a = 17.2985(9), b = 5.2538(3), c = 7.3912(4) A). All structures were ultimately refined by the Rietveld method.
- Masciocchi, Norberto,Ardizzoia, G. Attilio,Maspero, Angelo,Lamonica, Girolamo,Sironi, Angelo
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- Structural phase transitions in Zn(CN)2 under high pressures
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High pressure behavior of zinc cyanide (Zn(CN)2) has been investigated with the help of synchrotron-based X-ray diffraction measurements. Our studies reveal that under pressure this compound undergoes phase transformations and the structures of
- Poswal,Tyagi,Lausi, Andrea,Deb,Sharma, Surinder M.
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- Stitching 2D Polymeric Layers into Flexible 3D Metal-Organic Frameworks via a Sequential Self-Assembly Approach
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Two-dimensional (2D) coordination polymer [Zn(ATZ)2]n (HATZ = 5-amino-1H-tetrazole) featuring a 2D + 2D → 2D pillar-layer array was synthesized, wherein two honeycomb-shaped Zn(ATZ)1.5 sublayers can be stitched together by dicarboxylate bridging linkers of varied length and type to generate 4 three-dimensional (3D) isoreticular noninterperpentrated frameworks under solvothermal conditions. The interpenetration behavior may be constrained to some extent by the pillar length because a 3D twofold interpenetrated architecture was obtained with a longer ligand using a similar process. The pillar-exchange process enabled the facile synthesis of a family of isoreticular metal-organic framework structures with different flexibilities and interpenetration behaviors through the judicious choice of the type and size of the pillar units. Thermal analysis indicated that [Zn(ATZ)2]n also possesses excellent thermostability at a high decomposition temperature up to 356 °C. The kinetic parameters of its exothermic process were studied by Kissingers and Ozawa-Doyles methods. Furthermore, its luminescent properties at room temperature were also studied in detail.
- Zhang, Hao,Sheng, Tianlu,Hu, Shengmin,Zhuo, Chao,Li, Haoran,Fu, Ruibiao,Wen, Yuehong,Wu, Xintao
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- X-ray and Raman investigations on cyanides of mono- and divalent metals and synthesis, crystal structure and Raman spectrum of Tl5(CO3)2(CN)
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Pseudobinary cyanides of monovalent and divalent metals were synthesized, and X-ray and Raman data of the cyanides were measured. Single crystal X-ray structure analyses were performed on Zn(CN)2 (Pn3m (No. 224), a = 591.32(7) pm), Hg(CN)2 (I42d (No. 122), a = 969.22(14) and c = 890, 15(18) pm) and for the first time on AgCN (I42d (No. 166), a = 600.58(8) and c = 526.28(11) pm). The data are compared with literature data. The reaction of TlF and NaCN in 25% aqueous ammonia solution in air led to Tl5(CO3)2(CN) which was characterized by X-ray (Cmca (No. 64), 1468.1(3), 1171.6(2) and 1266.0(3) pm) and Raman spectroscopy.
- Reckeweg, Olaf,Simon, Arndt
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p. 895 - 900
(2007/10/03)
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- Copper-zinc oxide catalysts. Part IV. Thermal treatment in air, argon and hydrogen and XRD study of new bimetallic precursors - Direct formation of alloys
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Four new Cu-Zn bimetallic precursors of model catalysts for methanolization of syngas, Zn(NH3)2Cu(CN)3 (ZCA), [Zn(en)3]6[Cu5(CN)17]·nH 2O (n = 8.4) (ZCE3), [Zn(en)] [Cu(CN)3] (ZCE1) and [Zn1-xCux(en)] [Cu(CN)3] (ZCCE1), were thermally treated in air, hydrogen and argon atmosphere between 200 and 900°C. The calcinations in air yield firstly a mixture of cyano-ligand-containing compounds which transform at temperatures above 300°C to CuO and ZnO; the crystallite size of both oxides increases with temperature. The reduction in hydrogen at 300°C gives zinc cyanide and metallic copper which are converted at 450°C mainly to β′-brass including some α-and γ-alloys. The thermal treatment in argon displays the very high thermal stability of zinc cyanide to 900°C and formation of copper or α-CuZn alloy. Only the hydrogen treatment avoids the segregation of both metallic elements. The results are discussed on the basis of thermodynamic data.
- Kappenstein, Charles,?ernák, Juraj,Brahmi, Rachid,Duprez, Daniel,Chomi?, Jozef
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