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1.
1 INTRODUCTION The role played by CH…O hydrogen bonds in determining molecular conformation and crystal packing, in molecular recognition processes, in the stabilization of inclusion complexes, and possibly in the activity of biological macromolecules has been well established[1,2]. According to Desirajus structural setting for C-H贩稯 hydrogen bonds, the D (to define the C贩稯 contact distances) values within the range of 3.00~4.00 and the angles of CH…O with 150≤≤180 are stru…  相似文献   

2.
<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.  相似文献   

3.
1 INTRODUCTION Interest in metal phosphonate chemistry has in- creased in recent years, not only because of their rich structural chemistry[1~3] but also owing to their potential applications in catalysis, absorption and intercalation reaction[4~6]. The introduction of a se- cond metal-ligand component as a charge-compen- sating unit and structure-directing component into polyoxomolybdenum/oxovanadium organodi-phos- phonates has provided us a powerful method to syn- thesize this family o…  相似文献   

4.
A nickel-1,10-phenanthroline complex supported on an octamolybdate, [{Ni(phen)2}2(x- Mo8O26)], has been hydrothermally synthesized with MoO3, H2MoO4, Ni(OAc)2· 6H2O and 1,10-phenathroline (1,10-phen) as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.2952(2), b = 1.6659(10), c = 1.3956(12) nm, b =106.273(8)°, V = 2.8906(5) nm3, Z = 2. 5604 observable reflections (I >2s(I)) were used for structure resolution and refinements to converge to final R1 = 0.0414, wR2 = 0.0815. The result of structure determination shows that the compound contains octamolybdate possessing a novel structure type (named as x-isomer). The feature of x-[Mo8O26]4- is that it is composed of Mo6O6 ring and two MoO6 octahedra located at cap positions on opposite faces. The Mo6O6 ring contains two octahedral and four trigonal-bipyramidal MoVI atoms. Each x-[Mo8O26]4- unit is bonded with two [Ni(phen)2]2+ through terminal oxygen atoms of octahedral and neighbouring trigonal-bipyramidal Mo atom in the Mo6O6 ring. IR and UV-Vis spectra of the compound were measured and its electronic structure was studied by EHMO method.  相似文献   

5.
The new oxothiomolybdate anion [Mo8S8O8(OH)8[HWO5(H2O)]]3- (denoted HMo8W3-) has been synthesized in aqueous solution by an acido-basic condensation reaction. Four (Mo(V)2S2O2) building blocks are connected through hydroxo bridges around a central [W(VI)O6] octahedron. X-ray and neutron diffraction studies have been performed on single crystals of the lithium salt Li3[Mo8S8O8(OH)8[HWO5(H2O)]] x 18H2O (Li3HMo8W x 18H2O) in an aqueous grown from HMo8W3- solution of LiCl (1 M). The neutron diffraction experiment enabled us to locate both the protons and the lithium ions. In the structure of Li3HMo8W x 18H20, ring-shaped anions interleaved by a cluster of disordered hydrogen-bonded water molecules stack on top of each other along lithium pillars. The lithium columns are formed by alternating edge-sharing octahedra and tetrahedra, with one lithium site in four being totally vacant. Ionic conductivity measurements on pressed pellets have shown that Li3HMo8W x 18H2O is a good ionic conductor at room temperature (sigma = 10(-5) S cm(-1)), but the ionic conductivity on single crystals is smaller by two orders of magnitude and is isotropic; this suggests the main path of conduction involves surface protons rather than lithium ions of the bulk.  相似文献   

6.
A new molybdenum phosphate [Zn(Mov6P4O31H10)2(C4H14N3)2]·2C4H13N3·8H2O 1 (C4H13N3 = diethylenetriamine) has been synthesized under hydrothermal condition. Single-crystal X-ray diffraction reveals that compound 1 crystallizes in the monoclinic, space group P21/n, a =13.1679(3), b = 22.1240(6), c = 13.6146(3) (A), β = 103.4847(7)°, V = 3856.95(16) (A)3,C16H90N12O70P8ZnMo12, Mr = 3035.41, Z = 2, Dc = 2.614 g/cm3, μ = 2.483 mm-1, F(000) = 2968, S = 1.014, the final R = 0.0196 and wR = 0.0506 for 7486 observed reflections (I > 2σ(Ⅰ)). Compound 1 consists of two identical rings of six edge-sharing MoO6 octahedra interconnected by one ZnO6 octahedron, whereas the PO4 tetrahedra which share their apices with the MoO6 octahedra are only located on one side of each Mo6 ring. The 2-charge of polyanion [Zn(Mov6P4O31H10)2]2- unit is compensated in the crystal by two mono-protonated diethylenetriamines (C4H14N3)+. By hydrogen bonding interactions the polyanion of compound 1 is interconnected to form pseudo three dimensional molybdophosphate. Other characterizations by elemental analyses, IR spectrum and fluorescent spectrum are also described.  相似文献   

7.
The hydrothermal reaction of MoO(3) with BaH(3)IO(6) at 180 degrees C for 3 days results in the formation of Ba[(MoO(2))(6)(IO(4))(2)O(4)] x H(2)O (1). Under similar conditions, the reaction of Ba(OH)(2) x 8H(2)O with MoO(3) and Ba(IO(4))(2) x 6H(2)O yields Ba(3)[(MoO(2))(2)(IO(6))(2)] x 2H(2)O (2). The structure of 1, determined by single-crystal X-ray diffraction, consists of corner- and edge-sharing distorted MoO(6) octahedra that create two-dimensional slabs. Contained within this molybdenum oxide framework are approximately C(2v) tetraoxoiodate(V) anions, IO(4)(3-), that are involved in bonding with five Mo(VI) centers. The two equatorial oxygen atoms of the IO(4)(3-) anion chelate a single Mo(VI) center, whereas the axial atoms are mu(3)-oxo groups and complete the octahedra of four MoO(6) units. The coordination of the tetraoxoiodate(V) anion to these five highly electropositive centers is probably responsible for stabilizing the substantial anionic charge of this anion. The Ba(2+) cations separate the layers from one another and form long ionic contacts with neighboring oxygen atoms and a water molecule. Compound 2 also contains distorted MoO(6) octahedra. However, these solely edge-share with octahedral hexaoxoiodate(VII), IO(6)(5-), anions to form zigzagging one-dimensional, (1)(infinity)[(MoO(2))(IO(6))](3-), chains that are polar. These chains are separated from one another by Ba(2+) cations that are coordinated by additional water molecules. Bond valence sums for the iodine atoms in 1 and 2 are 5.01 and 7.03, respectively. Crystallographic data: 1, monoclinic, space group C2/c, a = 13.584(1) A, b = 7.3977(7) A, c = 20.736(2) A, beta = 108.244(2) degrees, Z = 4; 2, orthorhombic, space group Fdd2, a = 13.356(7) A, b = 45.54(2) A, c = 4.867(3) A, Z = 8.  相似文献   

8.
1 INTRODUCTION Hydrothermal synthesis of Mo(V) phosphates has allowed various structures, all characterized by the presence of identical clusters with the composition Mo12MP8X62 (X = O, OH) to be stabilized[1~6]. Many Mo(V) phosphates with such clusters have been iso- lated to date. The first compound was discovered by Haushalter and Lai[1] for M = Na with the formula (PPh4)2[(H3O)2NaMo6P4O24(OH)7]?5H2O. Recently, a second type of structure has been observed for M = Na (Na8(…  相似文献   

9.
The novel, functionalized heteropolymolybdates [RPMo(6)O(21)(O(2)CCH(2)NH(3))(3)](2)(-) (R = OH, CH(3), C(2)H(5), H) have been synthesized and characterized by IR, (31)P NMR spectroscopy, and elemental analysis. Single-crystal X-ray analysis was carried out on K(2)[HOPMo(6)O(21)(O(2)CCH(2)NH(3))(3)].8.5H(2)O, which crystallizes in the orthorhombic system, space group Pnma, with a = 14.118(2) A, b = 20.660(3) A, c = 12.191(2) A, and Z = 4; K(2)[H(3)CPMo(6)O(21)(O(2)CCH(2)NH(3))(3)].8.5H(2)O, which crystallizes in the orthorhombic system, space group Pnma, with a = 14.1643(6) A, b = 20.8658(8) A, c = 12.2235(5) A, and Z = 4; and K(2)[HPMo(6)O(21)(O(2)CCH(2)NH(3))(3)].8H(2)O, which crystallizes in the orthorhombic system, space group Pnma, with a = 14.092(3) A, b = 20.696(2) A, c = 12.199(4) A, and Z = 4. We also report on the synthesis and characterization of the isostructural derivative K(2)[H(5)C(2)PMo(6)O(21)(O(2)CCH(2)NH(3))(3)]. The four title polyanions consist of an RP (R = OH, CH(3), C(2)H(5), H) hetero group surrounded by a ring of six MoO(6) octahedra sharing edges and corners alternatingly. Three glycine molecules are each bound to two edge-sharing Mo centers via their carboxylate functionality on the same side of the ring. The central phosphorus atom is located slightly above the plane of the six molybdenums, and its terminal R group is on the same side of the ring as the glycines. NMR studies show that the solid state structures of the title compounds are preserved in solution.  相似文献   

10.
Cyclic oxothiomolybdates containing polyphosphate ions were prepared by simple reactions in aqueous medium of the corresponding polyphosphate ions and the cyclic precursor K(2)I(2)Mo(10)S(10)O(10)(OH)(10)(OH(2))(5).15H(2)O. K(5)[Cl(P(2)O(7)]Mo(12)S(12)O(12)(OH)(12)(H(2)O)(4)].22H(2)O (1) was isolated from concentrated chloride solution (2.5 mol.L(-1)). 1 reveals a remarkable complex containing two different substrates encapsulated in a dodecanuclear ring, a H-bonded Cl(-) ion, and a covalently bonded [P(2)O(7)] group. The chloride ion in 1 can be selectively removed for a monohydrogenophosphate group yielding K(6)[(HPO(4))(P(2)O(7))Mo(12)S(12)O(12)(OH)(12)(H(2)O)(2)].19H(2)O (2), a mixed species containing a [P(2)O(7)] and a [HPO(4)] group. The substitution is accompanied by a significant change of the ring, which adopts a "pear-shape" conformation. In the presence of triphosphate ion, the "heart-shaped" decanuclear ring Rb(3)[(H(2)P(3)O(10))Mo(10)S(10)O(10)(OH)(10)].17.5H(2)O (3) is formed containing a linear [P(3)O(10)] group intimately embedded in the inorganic cyclic host. The three compounds were structurally characterized by single-crystal X-ray diffraction. The behaviors of 1, 2, and 3 in solution were studied by (31)P NMR. Variable temperature experiments, supported by a two-dimensional COSY (31)P experiment, revealed that the supramolecular interaction existing between the chloride ion and the ring in solid 1 is maintained in solution. Nevertheless, 1 remains labile, and successive equilibria were evidenced and interpreted as an ion-pair association involving a halide ion (Cl, Br, or I), responsible for the conformational change of the [P(2)O(7)] group within the cavity. The influence of the nature of the halide guest (Cl(-), Br(-), and I(-)) on the successive equilibria was studied, and the thermodynamic constant related to the postulated equilibrium was determined. The stability of the supramolecular association decreases in the order Cl > Br > I. In solution, a phosphate exchange is observed for 2 while for 3 the absence of temperature dependence of the (31)P NMR spectrum confirms the conformation of the host-guest system is blocked. Elemental analysis and infrared characterizations are also supplied.  相似文献   

11.
The hydrothermal reactions of a Cu(II) starting material, a molybdate source, 2,2'-bipyridine or terpyridine, and the appropriate alkyldiphosphonate ligand yield two series of bimetallic organophosphonate hybrid materials of the general types [Cu(n)(bpy)(m)Mo(x)O(y)(H(2)O)(p)[O(3)P(CH(2))(n)PO(3)](z)] and [Cu(n)(terpy)(m)Mo(x)O(y)(H(2)O)(p)[O(3)P(CH(2))(n)PO(3)](z)]. The bipyridyl series includes the one-dimensional materials [Cu(bpy)(MoO(2))(H(2)O)(O(3)PCH(2)PO(3))] (1) and [[Cu(bpy)(2)][Cu(bpy)(H(2)O)](Mo(5)O(15))(O(3)PCH(2)CH(2)CH(2)CH(2)PO(3))].H(2)O (5.H(2)O) and the two-dimensional hybrids [Cu(bpy)(Mo(2)O(5))(H(2)O)(O(3)PCH(2)PO(3))].H(2)O (2.H(2)O), [[Cu(bpy)](2)(Mo(4)O(12))(H(2)O)(2)(O(3)PCH(2)CH(2)PO(3))].2H(2)O (3.2H(2)O), and [Cu(bpy)(Mo(2)O(5))(O(3)PCH(2)CH(2)CH(2)PO(3))](4). The terpyridyl series is represented by the one-dimensional [[Cu(terpy)(H(2)O)](2)(Mo(5)O(15))(O(3)PCH(2)CH(2)PO(3))].3H(2)O (7.3H(2)O) and the two-dimensional composite materials [Cu(terpy)(Mo(2)O(5))(O(3)PCH(2)PO(3))] (6) and [[Cu(terpy)](2)(Mo(5)O(15))(O(3)PCH(2)CH(2)CH(2)PO(3))] (8). The structures exhibit a variety of molybdate building blocks including isolated [MoO(6)] octahedra in 1, binuclear subunits in 2, 4, and 6, tetranuclear embedded clusters in 3, and the prototypical [Mo(5)O(15)(O(3)PR)(2)](4-) cluster type in 5, 7, and 8. These latter materials exemplify the building block approach to the preparation of extended structures.  相似文献   

12.
The novel, functionalized heteropolymolybdate [(O(2)CCH(2)PO(3))(2)Mo(5)O(15)](6-) (1) has been synthesized and characterized by IR and (31)P NMR spectroscopy and elemental analysis. Single-crystal X-ray analysis was carried out on Rb(4)KNa[(O(2)CCH(2)PO(3))(2)Mo(5)O(15)].H(2)O, which crystallizes in the monoclinic system, space group P2(1)/n, with a = 10.146(2) A, b = 13.704(3) A, c = 20.577(4) A, beta = 94.88(3) degrees, and Z = 4. The title polyanion consists of a ring of five MoO(6) octahedra with four edge junctions and one corner junction. This nonplanar arrangement is stabilized by two phosphonocarboxylate groups that are bound via their phosphonate functionalities on opposite sides of the ring. As a result the two dangling arms with their terminal carboxylate groups protrude away from the molybdenum-oxo framework in diametrically opposed directions. The solid-state structure of 1 is preserved in solution on the basis of NMR. We also report on the synthesis and characterization of the isostructural derivative [(O(2)CC(2)H(4)PO(3))(2)Mo(5)O(15)](6-) (2).  相似文献   

13.
[C6N2H18]2[Mo5O15(HPO4)2]·H2O的水热合成与结构表征   总被引:6,自引:0,他引:6  
通过水热法合成了一个新化合物[C6N2H18]2[Mo5O15(HPO4)2]·H2O,并通过IR光谱、ICP、元素分析、差热与热重分析和X射线单晶衍射分析等手段进行了表征.结果表明,晶体属三方晶系,P3(2)21空间群,a=1.1231(1)nm,c=2.2802(5)nm,V=2.4911(7)nm3,Dx=2.835Mg/m3,Z=6,最后的一致性因子R=0.0227,wR=0.0675.阴离子中Mo5O15构成一环状结构,2个HPO4一个连在环的下方,一个连在环的上方,形成类似于“飞碟”状的结构,阳离子为2个质子化的四甲基乙二胺.  相似文献   

14.
1 INTRODUCTION The synthesis of porous and open-framework transition metal phosphates has received great in- terest due to their various compositions and topolo- gyies, as well as their useful properties such as con- trollable size- and shape-selectivity, rigid frame- works and chemical/thermal stability[1]. Of these phosphates constructed from oxometal polyhedra and PO4 tetrahedron, the most interesting is the [MoV6P4X31]n- (X=O, OH) family with the dimen- sionalities ranging from …  相似文献   

15.
The reaction of potassium molybdate(VI) with biologically relevant ligands, citric and malic acids, in the presence of H2O2 was investigated for the effect of pH variations on the product pattern. That with citric acid led to the formation of the monomeric complex K4[MoO(O2)2(cit)].4H2O (1) in the pH range 7-9, and dimer K5[MoO(O2)(2-)(Hcit)H(Hcit)(O2)2OMo].6H2O (2) (H4cit = citric acid) at pH 3-6 through carboxylate-carboxylic acid hydrogen bonding. The relation with the previously identified K4[MoO3(cit)].2H2O (4) and K4[Mo2O5(Hcit)2].4H2O (5) were shown. These and other intermediates were shown to react in the pH range 3-6 to give a more stable species 2; the reaction sequence was demonstrated either by the protonation from 1 or the deprotonation of [MoO(O2)2(H2cit)](2-) (8). Evidence that 2 exists as a dimer in solution is presented. The reaction with (S)-malic acid afforded Delta-K(2n)[MoO(O2)2((S)-Hmal)]n.nH2O (3) (H3mal = malic acid) that was oxidized further to oxalato molybdate (11) by H2O2. The three complexes 1-3 were characterized by elemental analysis, UV, IR and NMR spectroscopies, in addition to the X-ray structural studies that show citrate and malate being coordinated as bidentate ligands via alpha-alkoxyl and alpha-carboxylate groups. The formation of these complexes is dictated by pH and their thermal stabilities varied with the coordinated hydroxycarboxylate ligands.  相似文献   

16.
Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36(OH)4[La(H2O)4]]5+ polyoxocation with glutarate (C5H6O(2)(2-)) and squarate (C4O(4)(2-)) organic ligands. [epsilon-PMo12O37(OH)3[La(H2O)4(C5H6O4)0.5]4].21 H2O (1) and [epsilon-PMo12O39(OH)[La(H2O)6]2-[La(H2O)5(C4O4)0.5]2].17 H2O (2) form unprecedented 1D chains built from alternating polyoxocations and organic ligands connected through LaO links. The structures of these materials are compared to the 2D hybrid organic-inorganic framework [NC4H12]2-[Mo22O52(OH)18[La(H2O)4]2[La(CH3CO2)2]4].8H2O (3) isolated from the hydrothermal reaction of elemental precursors (MoO(4)(2-), Mo, La3+) in acetate buffer. Compound 3 is built from previously undescribed polyoxometalate units with twenty-two MoV centers capped by six La3+ ions, four of which are bridged by acetate ligands.  相似文献   

17.
Levin D  Soled SL  Ying JY 《Inorganic chemistry》1996,35(14):4191-4197
A layered ammonium nickel molybdate was prepared by precipitation from a solution of nickel nitrate and ammonium heptamolybdate. The compound obtained, (NH(4))HNi(2)(OH)(2)(MoO(4))(2), is trigonal with hexagonal unit cell parameters a = 6.0147(4) ?, c = 21.8812(13) ?, and Z = 3. A powder X-ray diffraction pattern was obtained using synchrotron radiation. The structure was generated from three-dimensional Patterson and difference Fourier density maps and refined in the space group R&thremacr;m by the Rietveld method. The structure consists of molybdate tetrahedra and nickel octahedra forming layers perpendicular to the c axis. There are three layers per unit cell, with ammonium ions incorporated between the layers. The structure is a member of a solid solution series of (NH(4))H(2)(x)()Ni(3)(-)(x)()O(OH)(MoO(4))(2), where 0 相似文献   

18.
Photochromism of novel molybdate/alkylamine composite thin films.   总被引:1,自引:0,他引:1  
Novel inorganic/organic composite films of molybdates with photochromic properties have been prepared by self-assembly using alkylammonium ions as a supramolecular template. Both 1-hexadecylammonium/polyoxomolybdate (C16-Mo) and 1-octadecylammonium/polyoxomolybdate (C18-Mo) composite films have been successfully fabricated. The elemental analysis and thermal gravimetric analysis show that the main product in the C16-Mo film was (C16H33NH3)4Mo8O26. The X-ray diffraction (XRD) results indicate that the composite films were lamellar in nature. The IR, Raman and X-ray photoelectron spectroscopy (XPS) results show that the polyoxomolybdate anions present as MoO6 octahedra and that the Mo species exists as Mo6+ in the freshly prepared films. The alkyl chains in the 1-hexadecylammonium chains were linear and the alkyl groups are an all-trans configuration. Upon UV irradiation of the C16-Mo films, some Mo6+ was reduced to Mo5+, some -NH3+ became -NH2 with a concomitant increase in the concentration of -OH groups on the molybdate moieties, and the films were colored. Thus, the photochromism of the films involves the reduction of Mo6+ to Mo5+, coupled with a proton transfer from 1-hexadecylammonium ions to an oxygen atom at the Mo site. In contrast to thin films of transition-metal oxides, which all show photochromism in the blue region of the electromagnetic spectrum, these composite films show photochromism in the violet region with the greatest absorbance change at 472 nm.  相似文献   

19.
1 INTRODUCTION A new class of materials of metal oxide clusters based on anionic molybdenum phosphate frameworks has received much attention as a consequence of their potential applications in catalysis and materials science [1]. As a result, some molybdenum phosphates have been studied [2,3]. Recently we have studied the structure of NaPMO material[4] and the spectrum of multicomponent compound with Keggin struc- ture [5]. Here we report the synthesis and crystal structure of a new…  相似文献   

20.
A novel organotin-substituted polyoxomolybdate cluster (H(3)O)(16)[(H(2)O)(2)Mo(V)O(OH)](2){Mo(VI)(28)Mo(II)(4)(NO)(4)(BuSnO)(2)[BuSn(OH)(2)](2)O(102)(H(2)O)(12)}.18H(2)O was synthesized in a 'one-pot' reaction by adopting the reduction-oxidation-reconstitution self-assembly process, which shows a {Mo(34)(NO)(4)Sn(4)} mixed metal skeleton, which is constructed from two {Mo(16)(NO)(2)Sn(2)} subunits being linked by two MoO(6) octahedra.  相似文献   

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