Synthese und Struktur von Mo2NCl7

Synthesis and Structure of Mo₂NCl₇ The reaction of VN with MoCl₅ at 175 °C in a sealed glass ampoule yields the molybdenum(V) nitride chloride Mo₂NCl₇ in form of air sensitive black crystals with the triclinic space group P1¯ and a = 905.7(8); b = 975.4((6); c = 1283.4(8) pm, α = 103.13(4)°; β = 109.83(5)° und γ = 98.58(5)°. The crystal structure is built up from dinuclear units [Mo₂N₂Cl₇]^3— and [Mo₂Cl₇]³⁺, which are connected by asymmetric nitrido bridges to form endless chains. Within both dinuclear units the Mo atoms are bridged by three Cl atoms resulting in a Mo‐Mo distance of 349.2(3) pm in the unit [Mo₂N₂Cl₇]^3—. In case of [Mo₂Cl₇]³⁺, however, a shorter Mo‐Mo distance of 289.4(3) pm is observed, which can be interpreted by a single bond. Correspondingly a reduced magnetic moment of 0.95 B.M. per Mo atom is observed.     

Fabrications of some kinds of 2-D frameworks consisting of nanosized polyoxomolybdate anion [Mo36O112(H2O)16] via condensation processes

We succeeded to prepare novel [Mo₃₆O₁₁₂(H₂O)₁₆]⁸⁻ ({Mo₃₆}) compounds by using 1,3-diamino-2-propanol (βOHC₃-DA) and 1,3,5-tris(aminomethyl)benzene (MES-TA)+1,3-diaminopropane (C₃-DA) as linkers, and determined their crystal structures. We have confirmed they have unique two-dimensional (2-D) molybdenum oxide frameworks, which are formed by condensation of {Mo₃₆}s. Side-staggered arrays of {Mo₃₆}s, connected in lying position by eight bridges per a {Mo₃₆}, are formed in the compound with βOHC₃-DA, while herringbone arrays of {Mo₃₆}s, connected in standing position by four bridges per a {Mo₃₆}, are built in the compound with MES-TA+C₃-DA. The latter compound exhibited non-stoichiometric property, and its composition and cell parameters varied depending on the relative concentration of MES-TA in the mother solution.     

A series of Wells-Dawson and Keggin-based compounds with uncoordinated S donors as fluorescence sensors to Hg2+

Abstract

Through using a S-containing ligand 2,2’-dimethyl-4,4’-bithiazole (dbt), a series of Wells-Dawson and Keggin-based compounds, {Zn(dbt)₃}{Zn(dbt)₂(H₂O)}₂{HP₂W^VW^VI₁₇O₆₂}·4H₂O (1), {Cd(dbt)₂(H₂O) (HP₂W^VW^VI₁₇O₆₂)}{Cd(dbt)₃}{Cd(dbt)₂(H₂O)}·13H₂O (2), {Cd₂(dbt)₄Cl} {PW₁₂O₄₀} (3) and {Cd₂(dbt)₄}{SiW₁₂O₄₀} (4), were synthesized under hydrothermal conditions and structurally characterized. In 1, there are three dissociated subunits: Wells-Dawson anion, {Zn(dbt)₃}²⁺ and {Zn(dbt)₂(H₂O)}²⁺. In 2, the mono-supporting Wells-Dawson anions exhibit abundant hydrogen bonding interactions with discrete {Cd(dbt)₃}²⁺ and {Cd(dbt)₂(H₂O)}²⁺ mononuclear coordination complexes, constructing a supramolecular layer. Compound 3 has a binuclear Cd cluster {Cd₂(dbt)₄Cl}⁴⁺ with a Cl as a bridging atom. The Keggin anions link these binuclear Cd clusters alternately to build a 1D chain. In 4, a pair of {Cd(dbt)₂}²⁺ subunits connect adjacent Keggin anions and a 1D chain is formed. In these four compounds, only the N donors coordinate with Zn or Cd and the S atoms are uncoordinated. These compounds show good fluorescence sensing performance to Hg²⁺. We also studied the electrochemical and photocatalytic properties of 1–4. These compounds also can act as electrochemical sensors for the detection of nitrite.     

Binuclear oxomolybdenum(V) chlorides: Molecular structure of Mo2O4Cl2(DMF)4 and Mo2O4Cl2(bipy)2 · DMF

Reduction of MoO₂Cl₂(DMF)₂ (DMF = dimethylformamide) with PPh₃ in mild conditions afforded the dinuclear species Mo₂O₃Cl₄(DMF)₄. Related compounds could be prepared by substitution of DMF with stronger bases. While attempting to grow crystals of these compounds new complexes with the syn-[Mo₂O₄]²⁺ core were obtained. The molecular structures of Mo₂O₄Cl₂(DMF)₄, and Mo₂O₄Cl₂(bipy)₂ (bipy = 2,2′-bipyridine) have been established by X-ray diffraction analysis.     

Assembly of three supramolecular compounds based on [P2Mo5O23]6− and Ni(II) complexes

Three supramolecular compounds based on [P₂Mo₅O₂₃]^6? and Ni(II)–bim, [Ni(bim)₃]₃[P₂Mo₅O₂₃]·2H₂O (1), [Ni(Hbim)(bim)₂]₄[P₂Mo₅O₂₃]₂·3H₂O (2), and [Ni(bim)(Hbim)(phen)]₂[P₂Mo₅O₂₃]·7H₂O (3) (bim?=?2,2′-biimidazole, phen?=?1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction, IR, and TG. All the compounds show 3-D supramolecular networks constructed from weak interactions among free Ni(II) complex, water, and oxygens of [P₂Mo₅O₂₃]^6?. Compound 3 represents the first supramolecular example integrating {Ni(bim)(Hbim)(phen)} with Strandberg-type phosphomolybdate. The compounds display good electrocatalytic activity to reduce hydrogen peroxide and intense fluorescence properties in solution at room temperature.     

A series of Mixed-Valent Molybdenum Monophosphates,isotypic with leucophosphite represented by CsMo2P2O10 and K1.5Mo2P2O10 · H2O

The structure of two mixed valent molybdenum phosphates, CsMo₂P₂O₁₀ and K_1.5Mo₂P₂O₁₀ · H₂O has been solved from single crystals by X-ray diffraction in the space group P2₁/c with a = 9.428(1), b = 9.943(2), c = 12.348(2) Å and β = 127.38(1)° for CsMo₂P₂O₁₀ and a = 9.721(2), b = 9.805(3), c = 12.329(3) Å and β = 128.73(2)° for K_1.5Mo₂P₂O₁₀ · H₂O. These compounds isotypic with NH₄Mo₂P₂O₁₀ · H₂O and RbMo₂P₂O₁₀ · (1 ? x)H₂O exhibit the leucophosphite structure. The possibility of cationic non stoichiometry in this structure is also shown by the synthesis of two isotypic compounds A_1.5Mo₂P₂O₁₀ · xH₂O (A = Rb, Tl). In these monophosphates, one site Mo(1) is fully occupied by Mo^V, whereas the other octahedral site Mo(2) exhibits a variable valency Mo^III? Mo^IV to Mo^V. The main difference between these different phosphates deals with the distribution of the A cations inside the tunnels, depending upon their size and their content.     

A New Molybdophosphate Constructed From {Mo<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>O<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>}<Superscript>2+</Superscript> and 1-Hydroxyethylidenediphosphonate

A new molybdophosphate (NH₄)₈{Mo₂^VO₄[(Mo₂^VIO₆)CH₃C(O)(PO₃)₂]₂}·14H₂O (1), has been synthesized by the reaction of {Mo₂^VO₄(H₂O)₆}²⁺ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH₃)(PO₃H₂)₂), and it is characterized by ³¹P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion can be described as two {(Mo₂^VIO₆)(CH₃C(O)(PO₃)₂} units connected by a {Mo₂^VO₄}²⁺ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate.     

Chemical Adaptability: The Integration of Different Kinds of Matter into Giant Molecular Metal Oxides

Unique properties of the two giant wheel‐shaped molybdenum‐oxides of the type {Mo₁₅₄}≡[{Mo₂}{Mo₈}{Mo₁}]₁₄ ( 1 ) and {Mo₁₇₆}≡[{Mo₂}{Mo₈}{Mo₁}]₁₆ ( 2 ) that have the same building blocks either 14 or 16 times, respectively, are considered and show a “chemical adaptability” as a new phenomenon regarding the integration of a large number of appropriate cations and anions, for example, in form of the large “salt‐like” {M(SO₄)}₁₆ rings (M=K⁺, NH₄⁺), while the two resulting {Mo₁₄₆ (K(SO₄))₁₆} ( 3 ) and {Mo₁₄₆ (NH₄(SO₄))₁₆} ( 4 ) type hybrid compounds have the same shape as the parent ring structures. The chemical adaptability, which also allows the integration of anions and cations even at the same positions in the {Mo₄O₆}‐type units of 1 and 2 , is caused by easy changes in constitution by reorganisation and simultaneous release of (some) building blocks (one example: two opposite orientations of the same functional groups, that is, of H₂O{Mo?O} ( I ) and O?{Mo(H₂O)} ( II ) are possible). Whereas Cu²⁺ in [(H₄Cu^II₅)Mo^V₂₈Mo^VI₁₁₄O₄₃₂(H₂O)₅₈]^26? ( 5 a ) is simply coordinated to two parent O^2? ions of {Mo₄O₆} and to two fragments of type II , the SO₄^2? integration in 3 and 4 occurs through the substitution of two oxo ligands of {Mo₄O₆} as well as two H₂O ligands of fragment I . Complexes 3 and now 4 were characterised by different physical methods, for example, solutions of 4 in DMSO with sophisticated NMR spectroscopy (EXSY, DOSY and HSQC). The NH₄⁺ ions integrated in the cluster anion of 4 “communicate” with those in solution in the sense that the related H⁺ ion exchange is in equilibrium. The important message: the reported “chemical adaptability” has its formal counterpart in solutions of “molybdates”, which can form unique dynamic libraries containing constituents/building blocks that may form and break reversibly and can lead to the isolation of a variety of giant clusters with unusual properties.     

La5Mo6O21: a novel ternary reduced molybdenum oxide containing {MoIV}3 clusters and isolated MoV centres

The crystal structure of La₅Mo₆O₂₁ (penta­lanthanum hexa­molybdenum henicosa­oxide) is made up of Mo₃O₁₃ units containing triangular {Mo^IV}₃ clusters, three distorted Mo^VO₆ octa­hedral units and six inter­stitial La^III atoms. The Mo₃O₁₃ unit consists of three edge‐sharing Mo^IVO₆ units involving Mo—Mo bonding. The three Mo^VO₆ octa­hedra share their corners or edges with each other and with the Mo₃O₁₃ units.     

Dithiolylium‐Chlorooxomolybdate(V): Synthese und Kristallstruktur von (C3Cl3S2)[MoOCl4] und (C3Cl3S2)[Mo2O2Cl7]

Dithiolylium Chlorooxomolybdates(V): Synthesis and Crystal Structure of (C₃Cl₃S₂)[MoOCl₄] and (C₃Cl₃S₂)[Mo₂O₂Cl₇] The reaction of 3, 4, 5‐Trichlor‐1, 2‐dithiolylium chloride with MoOCl₃ in dichlormethane under solvothermal conditions at 65 °C simultaneously yields the green tetrachlorooxomolybdate(V) (C₃Cl₃S₂)[MoOCl₄] and the yellow‐brown heptachlorodioxodimolybdate(V) (C₃Cl₃S₂)[Mo₂O₂Cl₇]. The crystal structures of both compounds contain nearly planar (C₃Cl₃S₂)⁺ ions with a S—S bond length of 203 pm. The discrete [MoOCl₄]^— ion in the structure of (C₃Cl₃S₂)[MoOCl₄] has the shape of a square pyramid with the oxygen atom at the apex. The molybdenum atom is displaced by 58 pm from the basal plane towards the oxygen atom. The [Mo₂O₂Cl₇]^— ion in the structure of (C₃Cl₃S₂)[Mo₂O₂Cl₇] has the form of a face‐sharing double octahedron. It is formally composed of a [MoOCl₄]^— ion and a MoOCl₃ molecule connected by one symmetrical and two unsymmetrical chloro bridges. The molybdenum atoms placed in the centers of such connected octahedra are 357 pm apart, indicating no Mo—Mo bond.     

Synthesis,chemical and electrochemical studies of complexes of a tridentate ONS chelating ligand built around the elusive [MoVIOS]2+ core

Synthesis and characterization of four Mo(VI) complexes of a diprotic tridentate ONS chelating ligand (H₂L) containing the rather elusive [Mo^VIOS]²⁺ core is reported. These [Mo^VIOSL] complexes are obtained from their corresponding [Mo^VIO₂L] precursors using a combination of PPh₃ and PPh₃S. This process of oxo-abstraction and sulfido-inclusion affected by PPh₃–PPh₃S is reported for the first time and may be considered as a general method of converting [Mo^VIO₂L] complexes to the corresponding [Mo^VIOSL] complexes. Direct structural characterization of these complexes could not be done due to the ease of solvolysis of these oxosulfidomolybdenum(VI) complexes to the corresponding dioxomolybdenum(VI) analogues. However, the structure of these [Mo^VIOSL] complexes could be reasonably surmised from the corresponding structurally characterized [Mo^VIO₂L] complexes. Points of attachment of the potentially pentadentate but functionally tridentate ONS chelating ligands to [Mo^VIOS]²⁺ are located mainly through analysis of IR and UV-Vis spectral data and comparison with corresponding [Mo^VIO₂L] complexes of known structure. Conditions under which solvolysis of [Mo^VIOS]²⁺ to the [Mo^VIO₂]²⁺ core is significantly retarded have been identified and make us hopeful of obtaining single crystals of [Mo^VIOSL].     

Hydrothermal synthesis and crystal structure of a 1-D compound constructed from molybdovanadate clusters [V2Mo6O26]6− and copper complexes

A 1-D organic–inorganic hybrid compound, {Cu(en)₂}[V₂Mo₆O₂₆{Cu(en)₂}₂] · 4H₂O [en = ethylenediamine] (1), was hydrothermally synthesized and characterized by IR, UV spectroscopy, TG/DTA analyses, and single crystal X-ray diffraction. The X-ray crystallography analysis reveals an infinitely extended 1-D chain constructed from a molybdovanadate cluster [V₂Mo₆O₂₆]^6? as a building unit, two copper(II) complex fragments, {Cu(en)₂}²⁺, as attached groups and a copper(II) fragment, {Cu(en)₂}²⁺, as a bridging group. Each chain links to adjacent chains through weaker secondary Cu–O interactions forming an interesting 3-D supramolecular architecture.     

A novel Mo(V) diphosphate with an intersecting tunnel structure: Sr(MoO)2(P2O7)2

A novel Mo(V) diphosphate Sr(MoO)₂P₂O₇ has been synthesized. It crystallizes in the space group P2₁/n with a=7.925(1) Å, b=7.739(1) Å, c=9.485(1) Å and β=91.05(1)°. Its original framework consists of MoP₂O₁₁ units built up of one P₂O₇ group sharing two apices with one MoO₆ octahedron. The MoP₂O₁₁ units share corners, forming [MoP₂O₁₀]_∞ chains running along [101]. The assemblage of these chains forms the [Mo₂P₄O₁₆]_∞ intersecting tunnel framework. The Sr²⁺ cations are located at the tunnel intersection, showing a distorted cubic coordination. This structure is compared to those of Ba(MoO)₂P₂O₇ and LiMoOP₂O₇, which are also built up of MoP₂O₁₁ units forming [MoP₂O₁₀]_∞ chains, but with different configurations.     

Mo_2C/γ-Al_2O_3催化剂上苯加氢反应的原位红外光谱研究

采用程序升温反应法制备了钝化态、还原钝化态和新鲜态Mo2C/γ-Al2O3催化剂,结合原位红外光谱表征技术和反应性能评价,考察、比较了三种催化剂苯加氢反应活性.原位红外光谱结果表明,新鲜态Mo2C/γ-Al2O3催化剂在室温就显示了较好的苯加氢反应活性,表现了类贵金属的催化活性.CO吸附在反应前后新鲜态Mo2C/γ-Al2O3催化剂上的对比结果表明,低价态的Mo位(Moδ+(0δ2))是苯加氢反应活性中心.三种催化剂的反应活性结果表明,新鲜态Mo2C/γ-Al2O3催化剂反应活性最好,催化剂寿命最长,失活之后在500°C下H2处理即可恢复原有活性.     

Expanding the Hierarchy of Metal-Oxide Building Blocks from Fragments via Clusters to Networks: A ∞2 [({Mo17(NO)2}3{MoV2}3{FeIII}6)(FeII1.5)]-Type Layer Compound

A planar network consisting of {Mo₁₇(NO)₂}₃{Mo^V ₂}₃{Fe₆^III} cluster entities that are interlinked to layers via {Fe^II(H₂O)₄}²⁺ groups is formed stepwise from building units. The corresponding mixed-valence compound exhibits a variety of different formal oxidation states: {MoNO}³⁺, Mo^V, Mo^VI, Fe^II, and Fe^III. This compound also represents an extension of building-block hierarchy from the molecular level to extended networks.     

一个新颖镍配位阳离子修饰的还原型钼磷酸盐：Ni[Mo6O12(OH)3(PO4)(HPO4)3]2][Ni(H2O)2][Ni(H2O)(bipy)2]4·5H2O

水热合成并通过红外、热重、单晶X-射线衍射表征了一个新颖镍配位阳离子修饰的还原型钼磷酸盐,Ni[Mo₆O₁₂(OH)₃(PO₄)(HPO₄)₃]₂][Ni(H₂O)₂][Ni(H₂O)(bipy)₂]₄·5H₂O。单晶X-射线衍射研究表明,两个{Mo₆P₄}簇单元通过一个镍离子连接形成一个Ni[Mo₆P₄]₂二聚结构单元,其进一步和其他的镍配位阳离子连接成钼磷酸盐一维链状结构。在H₂O₂存在下的液－固体系中,使用该化合物催化氧化苯甲醛的探针反应结果表明,该化合物具有较高的催化氧化活性。     

Self‐Templating and In Situ Assembly of a Cubic Cluster‐of‐Clusters Architecture Based on a {Mo24Fe12} Inorganic Macrocycle

Engineering self‐templating inorganic architectures is critical for the development of bottom‐up approaches to nanoscience, but systems with a hierarchy of templates are elusive. Herein we describe that the cluster‐anion‐templated (CAT) assembly of a {CAT}?{Mo₂₄Fe₁₂} macrocycle forms a giant ca. 220 nm³ unit cell containing 16 macrocycles clustered into eight face‐shared tetrahedral cluster‐of‐clusters assemblies. We show that {CAT}?{Mo₂₄Fe₁₂} with different CATs gives the compounds 1 – 4 for CAT=Anderson {FeMo₆} ( 1 ), Keggin {PMo₁₂} ( 2 ), Dawson {P₂W₁₈} ( 3 ), and {Mo₁₂O₃₆(HPO₃)₂} ( 4 ) polyoxometalates. “Template‐free” assembly can be achieved, whereby the macrocycle components can also form a template in situ allowing template to macrocycle to superstructure formation and the ability to exchange the templates. Furthermore, the transformation of template clusters within the inorganic macrocycle {Mo₂₄Fe₁₂} allows the self‐generation of an uncapped {Mo₁₂O₃₆(HPO₃)₂} in compound 4 .     

Phase stability and ionic conductivity in substituted La2W2O9

Different substitutions, i.e. Sr²⁺, Ba²⁺, K⁺, Nb⁵⁺ and V⁵⁺, have been performed in the triclinic α-La₂W₂O₉ structure in order to stabilise the high temperature and better ionic conductor cubic β-phase. This approach has been used to try to obtain a new series of ionic conductors with LAMOX-type structure without molybdenum and presumably better redox stability compared to β-La₂Mo₂O₉. Nanocrystalline materials obtained by a freeze-drying precursor method at 600 °C exhibit mainly the β-La₂W₂O₉ structure, however, the triclinic α-form is stabilised as the firing temperature increases and the crystallite size grows. Only high levels of Ba²⁺ and V⁵⁺ substitutions retained the cubic form at room temperature after firing above 1100 °C. However, these phases are metastable above 700 °C, exhibiting an irreversible transformation to the low temperature triclinic α-phase. The synthesis, structure, phase stability, kinetic of phase transformation and electrical conductivity of these materials have been studied in the present report.