CRYSTAL STRUCTURE OF Na_2Mo_2O_4(EDTA)·5H_2O

<正> Introduction. Mo(V)-EDTA compounds have been widely studied. Recently, the title compound has been investigated by magnetic anisotropic method. In order to provide a detailed information on its structure, the crystal structure, of the title compound has been determined.     

Preparation and Molecular Structure of (SCZ)(TNPG)·2H_2O

1 INTRODUCTION 2,4,6-Trinitro-1,3,5-trihydroxybenzene(trinitro- phloroglucinol, TNPG) is a strong acidic organic com- pound with yellow needle crystal structure. There are three nitro-groups and three phenolic hydroxyl groups conjugated with the ring, so it is an important explosive. It can react with metallic compounds forming metallic salts of TNPG, which have strong combustion and detonating properties. The lead salt of TNPG has been extensively studied and recom- mended to use as…     

THE CRYSTAL STRUCTURE OF Mo_203[S_2P(OC_2H_5)_2]_4

<正> Introduction. In an attempt to synthesize Mo cluster compounds from the high-valenced Mo compounds in P_2S_5/EtOH-HC1 system we have obtained a brownblack rhombohedral crystal. The composition of it Mo_2O_3[S_2P(OC_2H_5)_2]_4 has been confirmed by X-ray single crystal structure determination, which reveals that the crystal structure is different from that by Knox, J. R. & Prout, C. K. (1969).     

Synthesis and Crystal Structure of [(NH_4)_6][Gd_2Mo_(36)O_(112)(H_2O)_(20)]·52H_2O

1 INTRODUCTION There is considerable interest in the heteropolymetalates in view of their potential applications in many fields, such as, catalysis, biology, medicine, magnetochemistry, and materials science[1～5]. It has been well- known that the rare earth elements are highly oxophilic and the anion of polyoxomolybdates have oxygen-rich composition, which can be used as synthons for the construction of novel heteropolymetalates. Since the structure of polyoxoanion 36-molybdate Mo36O1128…     

Preparation and Crystal Structure of a Rare-earth Salt Based on the Decavanadate (V_(10)O_(28)~(6-)): [Y(H_2O)_8]_2[V_(10)O_(28)]·9H_2O

1INTRODUCTION Contemporary interest in polyoxovanadates re-flects not only their attractive magnetic and electro-nic properties[1~3],but also the complex structural chemistry of vanadium with a variety of coordina-tion geometries and oxidation states[4].Decavana-date is a represent of the fully oxidized isopolyva-nadates.A number of compounds have been repo-rted and characterized[5~9],but it is found now that most of these polyvanadate salts coordinated with metal cations are actually eith…     

Synthesis and Structural Characterization of [(C_2H_5)_4N][V~((V))O_2(OC_6H_3(OCH_3)CHNNCSNH_2)]·H_2O

1 INTRODUCTIONAlthough vanadium plays an increasingly recognized role as a biometal[1~4], little is known about the structure and function of vanadium compounds in living organisms. A classical and nevertheless rapidly developing field of application for oxovanadates and related compounds is their use as catalysts in polymerization and oxidation reactions[5,6], and recent interest has focused on oxovanadates as model compounds for the interaction of oxovanadates with the active sites of en…     

Synthesis and Structure Characterization of Aqua-(μ_2-carbonato-O,O'''')-(2,2''''-bipyridyl)-copper(Ⅱ) Dihydrate

1 INTRODUCTION The class of materials of carbonato metal- organic compounds has received much attention as a consequence of their potential applications in biochemical and environmental protection[1～3]. Many carbonato compounds of Cu2+, Co3+ and Zn2+ etc. have been studied[4～6]. The carbonate anion is a versatile bridging ligand, which can bind metal cations in different modes to generate mononuclear, binuclear, trinuclear, tetranuclear and even 1D, 2D and 3D structures[4, 7, 8]. We…     

Synthesis and Crystal Structure of Na_(10)[LaSiW_(11)O_(39)(H_2O)_4]_2·22H_2O

1 INTRODUCTION The pseudoliquid character of heteropoly compounds as catalysts is determined by their crystallographic properties. Study on the crystal structures of the heteropoly compounds could provide interesting information to enrich heteropoly acid and catalytic chemistry[1]. In the past, Zhuo Ying-Li抯 group has synthesized the carbamidine salts of 1:1 LnL(Ln=lanthanide, L=[SiW11O39]n－)[2], and Pope抯 group has reported that -SiW11O39 units are connected by lanthanide catio…     

SYNTHESIS OF LANSFORDITE MgCO_3·5H_2O AND ITS CRYSTAL STRUCTURE INVESTIGATION

Euhedral crystals of the uncommon low-temperature mineral lansfordite have been obtained by the synthetic method, and the crystal structure analysis has been accomplished correspondingly. The structural parameters and the general view of structure were presented for the first time. The results obtained show that the coordination configuration of two magnesium ions in the unit cell is octahedral arrangement and the coordination number is 6, but in two forms: one in the complex ion Mg(CO_3)_2(H_2O)_4~(2-) and the other in the Mg(H_2O)_6~(2+). There is only a CO_3~(2-) group in the structure, not three distinct groups as reported by Hill et al. previously based on the IR absorption spectrum research data. The authors of this paper believe that the exact chemical formula of lansfordite should be expressed as "Mg(H_2O)_6. Mg(CO_3)_2 (H_2O)_4", and MgCO_3-5H_2O is only a simple chemical expression.     

Synthesis,characterization,properties and crystal structure of heterometallic 1D coordination polymers {[CuLZn·CuLZn(H_2O)]·H_2O}_n

Heterometallic complexes with novel structure have attracted much attention both from the material sci- ence and model study of metal enzymes[1―6]. Over the last two decades, a number of heterometallic binuclear complexes have been synthesized and investin- gated[7―9], many heterometallic polynuclear complexes have also been reported, but investigation of coordina- tion polymers is still very limited. One of the success- ful strategies in obtaining the desired heterometallic complexes is the…     

SYNTHESIS AND STRUCTURE OF TWO-ELECTRON HETEROPOLY BLUE K_2H_4SiMo(Ⅴ)_2Mo(Ⅵ)_(10)O_(40)·12H_2O WITH α-KEGGIN STRUCTURE

The single crystal of two-electron heteropoly blue with Si as the heteroatom and α-Keggin structure K_2H_4SiMo(Ⅴ)_2Mo(Ⅵ)_(10)O_(40)·12H_2O was obtained by electrolytic reduction. It crystallizes in a triclinic system with space group P , Mr=2117.73, a= 13.702(4), b=14.107(3), c=14.184(2) ; α=119.27(1), β=93.14(2), ;γ=110. 3(2)°, V=2154.29~3, Z=2, F(000)=1999, μ=36.39cm~(-1), Dc=3.26 g/cm~3. Final R factor is 0.0515. Mo(Ⅴ) is situated in two different edge-shared Mo_3O_(13) groups. The heteropoly blue was characterized by IR, UV, polarography, X-ray photoelectron spectra and ESR. All the results show that the structure of the heteropoly anion with Keggin structure remains unchanged basically in the process of reduction.     

Crystal Structure and Interaction with DNA of [Ni(phen)(mal)(H_2O)_2]·3H_2O

1 INTRODUCTION In the last few years, much attention has been paid to the molecular structure and biological activity of coordinated complexes in inorganic chemistry field. Ni(Ⅱ) is one of the commonest transition metals with two coordination numbers (4 and 6)[1～3]. Ge- nerally speaking, Ni(Ⅱ) coordination mode depends on the structure of ligand, solvent and reaction con- ditions, among which ligand plays a decisive role and determines not only the molecular structure of the complex bu…     

STUDY ON THE nd~a METAL REPLACED YBa_2Cu_(3-X)M_XO_(7-Y)

A systematic study of the structural and superconducting behavior of the high Tc compounds YBa_1Cu_(1.9)M_(0.1)O_(7-y) has been performed where M=Ti, V, Mn, Fe, Co, Ni, Zn, Zr, Nb, Mo, In and Sn. Structural analysis shows that most replacements somewhat modify the YBa_2Cu_3O_(7-y) lattice parameters in the orthorhombic structure, with the exception of Fe and Co which transit into tetragonal phase. Although the 1D Cu-O chains are destroyed, the depressed Tc remain within 73 to 76K in the case of Fe and Co. However. the substitution of Ni and Zn on the Cu_2 sites appears to strongly decrease Tc whereas their structure remains orthorhombic. This indicates that the 2D Cu-O planes play a very important role in the transportation of superconducting electrons but the 1D Cu-O chains play a role not only in supplying carrier number but also in coupling the Cu-O planes.     

Syntheses and Crystal Structures of Two New Metal Phosphonates:[Mn(H_2O)_2(C_(12)H_8N_2)(HO_3PCH_2CH_2CO_2)] and [Co(H_2O)_4(C_(10)H_8N_2)]·(HO_3PCH_2CH_2CO_2)

By the reactions of manganese(II) acetate, 2-sulfoethylphosphonic acid, 1,10-phen (1,10-phen = 1, 10-phenanthroline) or cobalt(II) acetate, 4,4'-bipy and 2-carboxyethylphosphonic acid, two novel compounds of [Mn(H2O)2(C12H8N2)(HO3PCH2CH2CO2)] (1) and[Co(H2O)4 (C10H8N2)]· (HO3PCH2CH2CO2) (2) have been synthesized and characterized by IR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound 1 has a 0D structure. Two Mn(II) ions are linked by two 2-carboxyethylphosphonic acid ligands, forming a centrosymmetric dimer. These dimers are further interlinked into a 2D layer structure by π-π stacking interactions and hydrogen bonds. Compound 2 has a 1D chain structure. The 2-carbo- xyethylphosphonic acid remains uncoor- dinated and acts as the organic template. By the bridge of 4,4'-bipy, the [Co(4,4'-bipy)]2+ chains are formed.     

Hydro(solvo)thermal Construction of a Copper Coordination Polymer Involving in Situ Ligand Synthesis: Preparation and Structure of [Cu_3(bdcO)_2(H_2O)_2]_n

1 INTRODUCTION Increasing attention has been paid to the coppercoordination polymer frameworks not only due totheir intriguing structure diversity but also theirpotential applications in the areas of molecular ad-sorption, catalysis, electromagnetism and photo-chemistry[1～4]. Incorporation of both organic and in-organic components in these compounds has createda new direction in searching for functional materialswith desired structures and properties. Over the lastdecades, the majority o…     

CRYSTAL STRUCTURE OF (Et_4N)_3[Mo_2Fe_6S_8(SPH)_9]

<正> Introduction. A series Of Mo-Fe-S complexes with doublecubane structure has been synthesized and identified. Because of the similarity of its extended X-ray absorption fine structure (EXAFS) to that of FeMo cofactor and nitrogenase, suggestion has been made that the doublecubane complexes may serve as models for the Mo site of nitrogenase. Therefore, the investigation of this type of complexes has attracted much attention. By using the similar method of spontaeous self-assembly reaction, and starting from certain kinds of Mo-Fe-S compounds, we have been able to obtain several kinds of compounds, one of which     

Application of Fe2O3/Al2O3 Composite Particles as Oxygen Carrier of Chemical Looping Combustion

Chemical looping combustion (CLC) of carbonaceous compounds has been proposed, in the past decade, as an efficient method for CO2 capture without cost of extra energy penalties. The technique involves the use of a metal oxide as an oxygen carrier that transfers oxygen from combustion air to fuels. The combustion is carried out in a two-step process: in the fuel reactor, the fuel is oxidized by a metal oxide, and in the air reactor, the reduced metal is oxidized back to the original phase. The use of iron oxide as an oxygen carrier has been investigated in this article. Particles composed of 80 wt% Fe2O3, together with Al2O3 as binder, have been prepared by impregnation methods. X-ray diffraction (XRD) analysis reveals that Fe2O3 does not interact with the Al2O3 binder after multi-cycles. The reactivity of the oxygen carrier particles has been studied in twenty-cycle reduction-oxidation tests in a thermal gravimetrical analysis (TGA) reactor. The components in the outlet gas have been analyzed. It has been observed that about 85% of CH4 converted to CO2 and H2O during most of the reduction periods. The oxygen carrier has kept quite a high reactivity in the twenty-cycle reactions. In the first twenty reaction cycles, the reaction rates became slightly higher with the number of cyclic reactions increasing, which was confirmed by the scanning electron microscopy (SEM) test results. The SEM analysis revealed that the pore size inside the particle had been enlarged by the thermal stress during the reaction, which was favorable for diffusion of the gaseous reactants into the particles. The experimental results suggested that the Fe2O3/Al2O3 oxygen carrier was a promising candidate for a CLC system.     

CRYSTAL AND MOLECULAR STRUCTURE OF GUANIDINIUM BIS (o-AMINOPHENYLARSENIC) HEXAMOLYBDATE (CN_3H_6)_4[(o NH_2C_6H_4 As)_2Mo_6O_(24)]

<正> Guanidinium bis (o - aminophenylarsenic) hexamolybdate belongs to monoclinic space group P21/c,with a=10. 217(2),b= 18. 870(2),c= 10. 939(2)A,β = 102. 82(3)°,Z = 2,V=2056. 4A3,and Dc=2. 477 g·cm-3. Each molecule contains one [(o-NH2C6H4As)2Mo6O24]4- anion and four CN3H6+ cations. In the anion,six distorted MoO6 octahedra are connected with edges-sharing to form a six-membered Mo ring which is capped above and below by two o - aminophenylarsenic groups. There is half a molecule in an asymmetric unit. It is interesting that both phenyl planes are almost perpendicular to the plane of the Mo atoms. The structure of the anion is similar to that of [ (CH3 As)2Mo6O24]4-,[(n-C3H7As)2Mo6O24]4- or [(C6H5CH2As)2Mo6O24]4-. This is the first example of this type of compounds in which the As atom is directly connected to a substituted phenyl group.     

THE STRUCTURAL BASIS OF THE POOR FIBRIN SPECIFICITY OF UROKINASE(Ⅰ)——KNOWLEDGE-BASED PREDICTION OF KRINGLE STRUCTURES OF UROKINASE AND ITS RELATED PROTEINS

The Kringle-1 structure of plasminogen (PGK-1), the Kringle-2 structure of tissue plasminogen activator (PAK-2) and the Kringle structure of prourokinase (UKK) has been modeled on the basis of the three-dimensional structure of Kringle-1 of prothrombin (PTK-1) at 2.8 resolution. The predicted three-dimensional structure of these Kringles shows that the binding site of PGK-1 is characterized by an apparent dipolar site, the polar parts of which are separated by a hydrophobic region. PAK-2 possesses the anionic center but has not a cationic binding center which might be provided by a guanidinium group from Arg-69 located adjacent to the Arg-71 position. UKK possesses neither the anionic binding center nor the cationic center which are probably the main reason for the poor fibrin specificity of urokinase.     

HYDROXYLATION OF BENZENE BY HETEROPOLY ACIDS(SALTS)CONTAINING VANADIUM

Direct hydroxylation of benzene catalyzed by vanadium-con-taining heteropoly compounds with Keggin or Dawson structure has beeninvestigated.The effects of several factors upon the hydroxylationreaction have also been examined.It is indicated that the highestyield of phenol reached 76%(based on H_2O_(?))with 99.4～100% selectivity.