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1.
Self assembly of NaVO3, Na2MoO4·2H2O and NiCl2·6H2O with the assistance of organic liginds under hydrothermal conditions results in two molybdovanadates [Ni(enMe)2]4{[Ni(enMe)2(H2O)]2[Ni(enMe)2][(VVMoVI8V4IVO40)(VIVO)2]2}·10H2O (1) and [Ni(enMe)2]5{[Ni(enMe)2]2[(VVMoVI4MoV4V4IVO40)(VIVO)4]2}·2H2O (2), (enMe = 1,2-diaminopropane), which have been characterized by single crystal X-ray diffraction analysis, IR spectroscopy, and elemental analysis. Both of the two compounds exhibit dumbbell-like structures constructed from capped polyoxomolybdovanadates and [Ni(enMe)2]2+ complexes. Polyoxoxanion 1 is composed of two bicapped Keggin-type anions [(VVMo8V4IVO40)(VIVO)2]7−, one [Ni(enMe)2]2+ bridging fragment and two decorated nickel(II) complexes. Polyxoxanion 2 consists of two tetracapped molybdenum-vanadium polyoxoanions [(VVMoVI4MoV4V4IVO40)(VIVO)4]7−, one [Ni(enMe)2]2+ bridging fragment and a nickel(II) decorated fragment. Polyxoxanions 1 and 2 are further linked to form three-dimensional supramolecular networks through extensive hydrogen bonding interactions. In addition, photocatalysis properties of these two compounds have been investigated.  相似文献   

2.
Three compounds based on the polyoxometalate building block [V12B18O60H6], (Na)10[(H2O)V12B18O60H6]·18H2O (1), Na8[Cu(en)2]2[V12B18O60H6](NO3)2·14.7H2O (2), Na7[Cu(en)2]2[V12B18O60H6](NO3)·15.5H2O (3), (en = ethylenediamine), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis and TGA. Compound 1 consists of polyoxovanadium borate [V12B18O60H6] clusters which are surrounded by sodium countercations in octahedral sites, stabilized by electrostatic interactions with the oxygen atoms of both vanadium and boron centres. However, compounds 2 and 3 correspond to more complicated structures, constructed from the same polyoxometalate clusters, which are interconnected by [Cu(en)2]2+ moieties via the terminal oxygen atoms of the polyoxoanions, generating one-dimensional structures. The functionalization of this polyoxovanadium borate cluster has been obtained by the use of [Cu(en)2]2+ complex ions, thus demonstrating the capacity of the terminal oxygen atoms of the cluster to bind transition metal centres. The structural stability of the [V12B18O60H6] cluster permits the formation of functionalized polyoxometalate clusters, generating various crystalline lattices.  相似文献   

3.
Nitrosyl derivatives of polyoxomolybdates have been synthesized and characterized by X-ray diffraction. Most of them contain the MoII(NO)3+ unit and their structures are related to the following structural types: Lindqvist, Keggin and decatungstate [W10O32]4–. Reductive nitrosylation of (NBu4)4[-Mo8O26] by hydroxylamine in methanol yields (NBu4)2[Mo5O13(OMe)4(NO){Na(MeOH)}]. 3MeOH, which is a versatile reagent yielding a variety of derivatives (i) by the transformation of [Mo5O13(OMe)4(NO)]3– into [Mo6O18(NO)]3– in acetonitrile, (ii) by the formation of [PMo12O39(NO)]4– by reaction of [Mo5O13(OMe)4(NO)]3– with [PMO12O40]3– in basic condition and (iii) by the formation of mixed valence MoVI/MoV/MoII decamolybdates [Mo10O24(OMe)7(NO)]2–, [Mo10O25(OMe)6(NO)] and [Mo10O20(OMe)9(NO)3]2– by chemical reduction of [Mo5O13(OMe)4(NO)]3–; MoII is localized while MoV are delocalized in the first two species but localized in the third. The unique ligating properties of [Mo5O13(OMe)4(NO)]3– have been documented: this species acts as a tetradentate ligand in [Ce{Mo5O13(OMe)4(NO)}2]2–, a symmetrically tetraligating ligand in [Rh2Cp*2(-Br){-Mo5O13(OMe)4(NO)}] and a bidentate ligand in [Mo5O13(OMe)4(NO){RhCp*(H2O)}]. Some polyoxomolybdates of the type [Mo5(NO)2O12{RC(NH2)NHO}2{RC(NH)NO}2]2–, which contain the Mo0(NO) 2 2+ unit, have also been characterized.  相似文献   

4.
The synergistic effect between polyoxometalates (POMs), namely K5[SiW11VVO40]·11H2O and H5[PMo10VV 2O40]·13H2O and laccase from ascomycete Myceliophthora thermophila has been employed for the first time in oxidative polymerization of catechol. Such a laccase-mediator system allowed the formation of a relatively high molecular weight polycatechol as confirmed by size exclusion chromatography and electrospray ionization mass spectrometry (ESI-MS) (3990 Da when using K5[SiW11VVO40]·11H2O and 3600 Da with H5[PMo10VV 2O40]·13H2O). The synthesized polymers were applied as dyes for the dyeing of flax fabrics. The color intensity of flax fabrics colored with polymer solutions was evaluated by diffuse reflectance spectrophotometry via k/s measurements (+10% of fixation ratio). A new synthetic process allowed a dyeing polymer, provided upon flax coloration, better color fixation and color resistance when compared to that obtained by conventional synthesis with laccase solely or with addition of organic mediator (1-hydroxybenzotriazole).  相似文献   

5.
Polyoxometalates for molecular devices: Antitumor activity and luminescence   总被引:8,自引:0,他引:8  
For the purpose of constituting a molecular device system based on the polyoxometalates, as well as a nonmolecular metal-oxide-based device system, we have worked energy and electron transfer processes induced by oxygen (O)-to-metal (M) charge transfer (OM LMCT) band photoexcitation and antitumoral and antiviral activities of certain polyoxometalates. This paper describes both antitumoral activity of polyoxomolybdates and luminescence involving in the energy transfer processes in the polyoxometalate lattice.[NH3Pri]6[Mo7O24].3H2O has been found to represent a potent antitumor activityin vivo against Meth-A sarcoma, MM-46 adenocarcinoma, and MX-1 human breast, OAT human lung, and CO-4 human colon cancer xenografts. The MoVO5(OH) site in the Mo7O24 framework exhibits a strong toxicity in contrast to the do-configurated MoVIO6 site but the antitutmoral potency of the former is similar to the latter. In conjunction with the fact that [Mo7O24]6– interacts with flavin mononucleotide (FMN) to yield a 1:1 complex which gives a redox potential 0.1 V more positive than FMN, the antitumor activity can be explained by the repeated redox cycles of [Mo7O24]6– in tumor cells, which would inhibit the ATP generation coupled with the electron transfer from NADH to coenzyme Q in/on the mitochondria.The intramolecular energy transfer from the OM LMCT excited states to Eu3+ in the polyoxometaloeuropate lattices such as Na9[EuW10O36].32H2O, K15H3[Eu3(H2O)3(SbW9O33)(W5O18)3].25.5H2O, [NH4]12H2[Eu4(H2O)16(MoO4)(Mo7O24)4].13H2O, and Eu2(H2O)12[Mo8O27].6H2O is investigated with a help of crystal structures. The M-O-M and Eu-O-M bond angels of about 150° provided the hopping of d1 electron among MO6 octahedra and to EuO8 (or EuO9) site with a resultant increase in the recombination between the electron and hole in the lattice. The coordination of aqua ligands to Eu3+ decreases liftime of the5Do emitting state, due to the vibronic coupling with the vibrational states of high frequency OH oscillators. A dispersion-typed electroluminescence (EL) cell based on [EuW10O36]9– is exemplified. With a.c. excitation to the cell the [EuW10O36]9– layer exhibits EL which matches the photoluminescence spectrum of the solid.Broad luminescence from the OM LMCT triplet states for polyoxometalates is also found below 100K. The localization of the OM LMCT triplet excitation energy at the MO6 octahedra results in an increase of the emission yield. The luminescence properties of Anderson-type polyoxometalates of K5.5H1.5[SbW6O24].6H2O and Na3H6[CrMo6O24].8H2O are discussed.  相似文献   

6.
In most aqueous polyoxometalate systems, numerous, often highly negatively charged species, are formed. To establish the speciation in such complex polyanion systems, many experimental methods and techniques must be used. Moreover, it is of vital importance that the experimental data are of the highest accuracy and that the data collected from different methods are treated simultaneously with an appropriate computer program. In systems containing one or more sensitive NMR nuclei, a combined EMF-NMR method has been shown to be extremely powerful.This article firstly gives some general comments on equilibria in aqueous polyoxometalate systems including ionic medium effects, and then describes an equilibrium EMF-NMR (31P and51V) study of the five component system H+-Mo(VI)-V(V)-P(V)-e. The study has been focused on so-called Keggin ratio solutions, Mo+V):P=12:1, since these are commonly used in selective oxidation processes. Special attention has been given to Mo10V2P and Mo9V3P solutions, where positional isomers occur. We have been able to identify and characterize all the five possible isomers of -Mo10V2PO 40 5– at 25 and 90 °C. Besides the results from the five component system, some interesting findings from the binary, ternary and quarternary sybsystems are also reported.  相似文献   

7.
Four new polyoxometalate compounds, namely [Cu2(pyrazine)4][Cu(pyrazine)2][PMo12O40] · 2H2O (1), {[K(H2O)2]4H8PW12O44}F · 8H2O (2), H9[K2KMo36O112(H2O)34] · 35H2O (3), and H3Na3[V10O28] · 15H2O (4), were prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. Single crystal X-ray diffraction analysis results reveal that, in compound 1, Keggin anion of [PMoO12O40]3− is enchased in the bowl-like Cu(I)-pyrazine intervals via weak interactions between terminal oxygen atoms and cations of Cu(I). For compound 2, a three-dimensional architecture with pores of 7.70 × 7.70 Å is constructed from the anions of [PW12O44]11− cross-linked via corner-sharing alkali cations of K+. The [Mo36O112(H2O)16]12− units of compound 3 are linked to form one wave-like chain via cations of K+. Whereas, in compound 4, anions of [V10O28]3− are linked via NaO6 octahedra to form two-dimensional layer structure. On the basis of this two-dimensional layer, a three-dimensional architecture is further formed via hydrogen bonds involving edge-shared NaO6 double octahedron.  相似文献   

8.
A new germanium-polyoxovanadate, (H3aep)4[V14Ge8O50]·2(aep)·13H2O (1), has been synthesized under solvothermal conditions applying GeO2, NH4VO3, Cu(NO3)2·3H2O and an aqueous solution of 1-(2-aminoethyl)-piperazine (aep, C6H18N3) in the temperature range from 110 to 150 °C. The compound crystallizes in the non-centrosymmetric tetragonal space group P-421c with = 17.193(1) Å, = 16.501(1) Å, V = 4877.9(5) Å3 and Z = 2. The structure consists of isolated spherical [VIV14GeIV8O50]12− cluster anions and protonated amine molecules as counterions. The cluster anion can be viewed as a derivative of the [V18O42] archetype by replacing four VO5 pyramids by four Ge2O7 units. The latter are formed by corner-sharing of two [GeO4]4− tetrahedra. At temperatures above 150 °C the compound (H2pip)4(Hpip)4[VIV14GeIV8O50(H2O)] (2) (pip = piperazine, C4N2H10) is formed and during the reaction Cu2+ is reduced to elemental copper. This redox reaction is essential for the formation of 2. The crystal water molecules in the structure of 1 are emitted at low temperatures. The magnetic properties are dominated by strong intra-cluster antiferromagnetic coupling and the strongest exchange between edge- and corner-sharing VO5 square pyramids results in an eight-membered spin ring to which two three-membered spin bridges are joined. The magnetic susceptibility data suggest that even at the low temperature of 2 K several multiplet states are still significantly populated.  相似文献   

9.
Seven new organic-inorganic hybrid compounds containing inorganic polyoxometalates and trigonal organic ligand 2,4,6-tris-(3/4-pyridyl)-1,3,5-triazine (3/4-tpt), namely [Mo8O26M(Htpt)2(H2O)2]n (M = Zn (1), Co (2), Ni (3)), [Mo8O26Cu(Htpt)2(H2O)2]n·2nH2O (4), [Mo8O26(H2tpt)2]·6H2O (5), [Mn(Mo4O13)(4-tpt)2]n (6) and [Fe3(Mo4O15)(3-tpt)]n·nH2O (7), were synthesized hydrothermally and characterized by EA, IR, TG, and PXRD techniques. Single crystal X-ray structural analysis revealed that compounds 1-4 are 1-D coordination polymers constructed from [Mo8O26]4− cluster and [M(Htpt)2(H2O)2]4+ fragments. Compound 5 is an isolated cluster composed of [Mo8O26]4− anion and monodentate H2tpt2+ cation. 3-Tpt ligands in 1-5 are partially protonated and act as monodentate ligands. Octamolybdates adopt β- and γ-[Mo8O26]4− structural mode in compounds 1-4 and 5, respectively. In compound 6, each [Mo4O13]2− tetramer links four Mn(II) ions to form a 2-D wave-like polymeric layer. The 2-D [MnMo4O13] bimetallic layers are pillared by neutral 4-tpt bidentately to generate a 3-D metal-organic framework. Compound 7 is a 3-D coordination polymer constructed from 2-D [Fe3(Mo4O15)] bimetallic polymeric layer and pillared by neutral tridentate 3-tpt. These compounds are thermal stable under 250 °C. The compounds 1 and 5 display luminescence with emission maximum at 481 and 442 nm, respectively.  相似文献   

10.
A series of malonato complexes of molybdenum(V) was prepared by reacting (PyH)5[MoOCl4(H2O)]3Cl2 or (PyH)n[MoOBr4]n with malonic acid (H2mal) or a half-neutralized acid, hydrogen malonate (Hmal), at ambient conditions: (PyH)3[Mo2O4Cl42-Hmal)] · CH3CN (1), (PyH)3[Mo2O4Br42-Hmal)] · CH3CN (2), (PyH)2[Mo2O4Cl(η2-mal)(μ2-Hmal)Py] (3), (3,5-LutH)2(H3O) [Mo2O42-mal)22-Hmal)] (4), (PyH)[Mo2O4Cl22-Memal)Py2] (5), (3,5-LutH)[Mo2O4Cl22-Memal)(3,5-Lut)2] (6), (PyH)[Mo2O4Cl22-Etmal)Py2] (7), (3,5-LutH)[Mo2O4Cl22-Prmal)(3,5-Lut)2] (8) and [{Mo2O42-Memal)Py2}22-OCH3)2] (9) (where Py = pyridine, C5H5N; PyH+ = pyridinium cation, C5H5NH+; 3,5-Lut = 3,5-lutidine, C7H9N; 3,5-LutH+ = 3,5-lutidinium cation, C7H9NH+; mal2− = malonate, OOCCH2COO; Memal = monomethyl malonate, OOCCH2COOCH3; Etmal = monoethyl malonate, OOCCH2COOC2H5 and Prmal = monopropyl malonate, OOCCH2COOC3H7). The complex anions of compounds 1-8 have a common structural feature: a dinuclear, singly metal-metal bonded {Mo2O4}2+ core with the carboxylate moiety of the malonato ligand coordinated in a syn-syn bidentate bridging manner to the pair of metal atoms. The remaining four coordination sites of the {Mo2O4}2+ core are occupied with halides in 1 and 2, with halides/pyridine ligands in 5-8, with a pair of bidentate malonate ions in 4 and with the combination of all in 3. The neutral molecules of 9 consist of two {Mo2O4}2+ cores linked with a pair of methoxide ions into a chain-like, tetranuclear cluster. An esterification of malonic acid was observed to take place in the reaction mixtures containing alcohols. Solvothermal reactions with malonic acid carried out at 115 °C produced anionic acetato complexes as found in (PyH)[Mo2O4Cl22-OOCCH3)Py2] · Py (10), (PyH)[Mo2O4Cl22-OOCCH3)Py2] (11), (3,5-LutH)[Mo2O4Cl22-OOCCH3)(3,5-Lut)2] (12) and (4-MePyH)3[Mo2O4Cl22-OOCCH3)(4-MePy)2]2Cl (13) (4-MePy = 4-methylpyridine, C6H7N). The acetate coordinated in the syn-syn bidentate bridging mode in all. Reactions of (PyH)5[MoOCl4(H2O)]3Cl2 with succinic acid (H2suc) at ambient conditions resulted in a complex with a half-neutralized acid, (PyH)[Mo2O4Cl22-Hsuc)Py2] · Py (14) (Hsuc = hydrogen succinate, OOC(CH2)2COOH), while those carried out at 115 °C in a tetranuclear succinato complex, (4-MePyH)2[{Mo2O4Cl2(4-MePy)2}24-suc)] (15) (suc2− = succinate, OOC(CH2)2COO). The tetranuclear anion of 15 consists of two {Mo2O4}2+ cores covalently linked with a tetradentate succinato ligand. The compounds were fully characterized by infrared vibrational spectroscopy, elemental analyses and X-ray diffraction studies.  相似文献   

11.
The reactions of the Keplerate super cluster [Mo132O372(CH3CO2)30(H2O)72]42− with a Cu(II) source and an organonitrogen donor in methanol/DMF solutions yielded a series of bimetallic organic-inorganic oxide hybrid materials, including the molecular species [Cu(phen)2MoO4] (1) and [{Cu(terpy)}2(MoO4)2] (2) and a series of materials constructed from the tetranuclear building block {Mo4O10(OMe)6}2−: the molecular [{Cu2(phen)2(O2CCH3)2 (MeOH)}Mo4O10(OMe)6] (3), [{Cu(terpy)(O2CCH3)}2Mo4O10(OMe)6] (4) and [{Cu(terpy)Cl}2Mo4O10(OMe)6] (5), the one-dimensional phases [{Cu(bpy)(HOMe)2}Mo4O10(OMe)6] (6), [{Cu(bpy)(DMF)2}Mo4O10(OMe)6] (7), [{Cu(bpa)(DMF)2}Mo4O10(OMe)6] (8), [{Cu(phen)(DMF)2}Mo4O10(OMe)6] (9) and [{CuCl(dpa)}2Mo4O10(OMe)6] (10), and the two-dimensional material [{Cu2(DMF)2(pdpa)}{Mo4O10(OMe)6}2] (11). When methanol is replaced by the tridentate alkoxide tris-methoxypropane (trisp), the {Mo2O4(trisp)2}2− cluster building block is observed for [Cu(phen)Mo2O4(trisp)2] (12), [Cu(bpa)(DMF)Mo2O4(trisp)2] (13) and [{Cu(bpy)(NO3)}2Mo2O4(trisp)2] (14).  相似文献   

12.
Hydrothermal reactions of V2O5, 1,4-phenyldiphosphonic acid and an appropriate organoamine, in the presence of HF as solubilizer, were exploited to prepare a series of materials of the general type [organoammonium cation]n[VxOy(HmO3PC6H4PO3Hp)3]. Compound 1, [H3N(CH2)4NH3][V2O4(O3PC6H4PO3)], exhibits a one-dimensional V-P-O substructure, linked through the phenyl tethers of the ligand into a layer. Compound 1 is a unique example of a V(V)-diphosphonate phase. Compounds 2 and 3, [H3N(CH2)2NH3][V2O2(O3PC6H4PO3H)2] and [H2pip][V2O2(O3PC6H4PO3H)2] (H2pip = piperazinium), exhibit identical two dimensional substructures, constructed from ribbons connected through the phenyl tethers of the ligands. The three-dimensional framework of [H3N(CH2)7NH3]2[V3O4(O3PC6H4PO3)2] (4) consists of V-P-O layers characterized by trinuclear V(IV)-oxide subunits and 9 and 12 polyhedral connect rings; the layers are buttressed by the phenyl spacers to provide the typical “pillared” layer structure common to metal diphosphonate materials. Compound 5, [H2dabco][V2F3O2(O3PC6H4PO3H)]·H2O, is also three-dimensional with oxyfluoro-vanadium(IV) chains linked through the diphosphonate ligands into a framework structure with void spacers to accommodate the {H2dabco}2+ cations (dabco = diamino bicyclo octane). The magnetic properties of 2-5 reflect the structural characteristics of the materials.  相似文献   

13.
Polyoxovanadates are inhibitors to various phosphate-metabolizing enzymes. The question arises of how the cluster is bound to the protein matrix. This paper describes oxovanadates with carboxylate and hydroxide ligands in the periphery of the cluster, which may be considered to model oxovanadate binding to carboxylic and alcoholic side-chain functions of the protein. Examples for complexes carrying alkoxo ligands dealt with in this article are dinuclear vanadate(V) esters, and hexa-, octa- and decanuclear, mixed-valence (VV/VIV) clusters, the latter related to decavanadate. The possible role of dimeric vanadate esters as transition state anologues in enzymatic phosphoester cleavage is addressed. Examples for carboxylate complexes are the mononuclear, seven-coordinate mixed anhydride between orthovanadic acid and pivalic acid, containing the carboxylate in the bidentate mode, tetra-, penta- and hexanuclear VIV/VV clusters with bridging carboxylate, and trinuclear VIV and VII/VIII clusters, bridged by carboxylates and trebly bridged by O2–. Special attention is given to a comparison of the bowls containing a V4(-O)3(-OH)(O2CR)4 and V4(-O4(O2CR)4 core, respectively, which can accomodate a K+ or a NO 3 .51V NMR spectroscopy is shown to be a useful tool, in many cases, for the vanadium speciation of complex systems.  相似文献   

14.
A new three-dimensional open framework structure of mixed valence ethylenediamine-vanadium phosphate [C2H10N2][(HVIVO3)(HVVO2)(PO4)] (1), has been synthesized under mild hydrothermal conditions and characterized by elemental analyses, IR, fluorescent spectrum, TG-DTA and single crystal X-ray diffraction. Compound 1 exhibits a novel three-dimensional (3D) vanadium phosphate anion framework composed of vanadium, phosphate, and oxygen atoms through covalent bonds, with the diprotonated ethylenediamine [NH3CH2CH2NH3]2+ cations residing in the channels along c-axis. The organic diprotonated ethylenediamine cations interact with the O atoms in the inorganic network through hydrogen bonds. The electrochemical behavior of 1 has also been studied in detail by cyclic voltammograms, which is very important for practical applications in electrode modification. Furthermore, the strong photoluminescence property of compound 1 is also measured at room temperature.  相似文献   

15.
CO dehydrogenase (CODH) is an environmentally crucial bacterial enzyme that oxidizes CO to CO2 at a Mo–Cu active site. Despite the close to atomic resolution structure (1.1 Å), significant uncertainties have remained with regard to the protonation state of the water-derived equatorial ligand coordinated at the Mo-center, as well as the nature of intermediates formed during the catalytic cycle. To address the protonation state of the equatorial ligand, we have developed a realistic in silico QM model (~179 atoms) containing structurally essential residues surrounding the active site. Using our QM model, we examined each plausible combination of redox states (MoVI–CuI, MoV–CuII, MoV–CuI, and MoIV–CuI) and Mo-coordinated equatorial ligands (O2?, OH?, H2O), as well as the effects of second-sphere residues surrounding the active site. Herein, we present a refined computational model for the Mo(VI) state in which Glu763 acts as an active site base, leading to a MoO2-like core and a protonated Glu763. Calculated structural and spectroscopic data (hyperfine couplings) are in support of a MoO2-like core in agreement with XRD data. The calculated two-electron reduction potential (E = ?467 mV vs. SHE) is in reasonable agreement with the experimental value (E = ?558 mV vs. SHE) for the redox couple comprising an equatorial oxo ligand and protonated Glu763 in the MoVI–CuI state and an equatorial water in the MoIV–CuI state. We also suggest a potential role of second-sphere residues (e.g., Glu763, Phe390) based on geometric changes observed upon exclusion of these residues in the most plausible oxidized states.  相似文献   

16.
A series of aryldiazenido polyoxomolybdates of the type (nBu4N)2[Mo5O13(OMe)4(NNAr){Na(MeOH)}] (Ar = C6F5, 1; Ar = O2N-o-C6H4, 2; Ar = O2N-m-C6H4, 3; Ar = O2N-p-C6H4, 4a; Ar = (O2N)2-o,p-C6H3, 5) have been obtained by controlled degradation of the parent compounds (nBu4N)3[Mo6O18(NNAr)] with NaOH in methanol. They have been characterized by elemental analysis and UV-Vis and IR spectroscopy. In addition, 4a has been characterized by 95Mo NMR spectroscopy and the crystal structure of (nBu4N)2[Mo5O13(OMe)4(NNC6H4-p-NO2){Na(H2O))]·H2O (4b) has been determined by X-ray diffraction. The molecular structure of the anion of 4b features a lacunary Lindqvist-type anion [Mo5O13(OMe)4(NNC6H4-p-NO2)]3− interacting with a sodium cation through the four terminal axial oxygen atoms. The 1:1 sodium complexes react with BaCl2 and BiCl3 to yield 2:1 complexes which have been isolated as (nBu4N)4[Ba{Mo5O13(OMe)4(NNAr)}2] (Ar = C6F5, 6; Ar = O2N-p-C6H4, 7) and (nBu4N)3[Bi{Mo5O13(OMe)4(NNAr)}2] (Ar = C6F5, 8; Ar = O2N-p-C6H4, 9). X-ray crystallography analysis of 9·Me2CO has shown that the tetradentate [Mo5O13(OMe)4(N2C6H4-p-NO2)]3− anions provide a square-antiprismatic environment for Bi. In contrast, IR spectroscopy provides evidence for a square-prismatic environment of Ba in 6 and 7. In acetonitrile-methanol mixed solvent, [Mo5O13(OMe)4(NNAr)]3− and [PW11O39]7−, generated in situ by alkaline degradation of their respective parents, [Mo6O18(NNAr)]3− and [PW12O40]3−, react together to give the Keggin-type diazenido compounds (nBu4N)4[PW11O39(MoNNAr)] (Ar = O2N-o-C6H4, 10; Ar = O2N-m-C6H4, 11; Ar = O2N-p-C6H4, 12), which have been characterized by 31P and 183W NMR spectroscopy.  相似文献   

17.
Molybdenum tetramers: Mo43-O)4[μ-O2P(CH2Cl)2]4O4 (1), Mo43-O)4(μ-O2P(CH2OH)2)4O4 (2), Mo43-O)4[μ-O2P(PhOMe)2]4O4 (3), and Mo43-O)4[μ-O2P(o-C6H4(CH2)2)]4O4 (4) have been synthesized and characterized by IR, UV-Vis, and 31P NMR spectroscopy. Molybdenum tetramers 1 and 4 along with the ligands L2A and L4 were structurally characterized by single crystal X-ray crystallography. An infinite 2D polymeric sheet was formed via inter and intra hydrogen bonds in the crystals of L2A. The crystals of L4 consist of infinite polymeric chains formed through hydrogen bonding. All molybdenum tetramers were tested as catalysts for the epoxidation of cis-cyclooctene in the presence of H2O2. Compounds 1 and 2 resulted in more than 80% epoxide after 24 hours at 70 °C, and displayed superior catalytic activities over compounds 3 and 4 under identical conditions. The superior catalytic activities of compounds 1 and 2 may be attributed to their better solubility in the ethanol/H2O2 system.  相似文献   

18.
A novel bifunctionalized arylimido derivative of hexamolybdate, (Bu4N)2[Mo6O17(NAr)2] [Ar = 2,6-(CH3)2C6H3] (1), in which the two 2,6-dimethylaniline groups are bounded to hexamolybdate at the cis positions, was synthesized by a facile reaction of α-octamolybdate with 2,6-dimethylaniline using DCC as a dehydration agent. The existence of strong non-typical C-H?O hydrogen bonds plays an important role in crystal structure stabilization of compound 1. The results of fluorescence spectra show that the formation of a covalent bond between 2,6-dimethylaniline molecule and hexamolybdate could efficiently quench the fluorescence intensity of 2,6-dimethylaniline molecule, with a fluorescence quencher efficiency of 87.7%. Thermal analysis results indicate that two substituted 2,6-(CH3)2C6H3 molecules bonding to the same cluster dissociated at different temperature, in well agreement with the different MoN bond length in compound 1. The electrochemical behavior of modified 1-CPE has been studied in detail. Compared with the conventional polyoxometalate (POM)-modified electrode, 1-CPE presents a merit of remarkable stability over 500 cycles due to the insolubility of the POM nanoparticles, which is especially important for practical applications.  相似文献   

19.
A new inorganic-organic hybrid complex, Na2[{Ag10(NC5H4COO)8(H2O)6}(SiW12O40)] (1), has been successfully synthesized from [SiW12O40]4− anions, Ag+ ions and 1,3-bis(4-pyridyl)propane under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, TG analyses, and single-crystal X-ray diffraction. In complex 1, each [SiW12O40]4− anion connects with six Ag atoms and in turn each Ag atom links to three [SiW12O40]4− anions, leading to a (6, 3) layer. Such (6, 3) layers are arranged in parallel and further linked by [Ag(H2O)(NC5H4COOH)2] fragments to generate a 3D framework. The most striking feature in this work is that 1,3-bis(4-pyridyl)propane converses to isonicotinic acid in the synthetic reaction of 1, which may be induced by the combined function of Ag+ ion and polyoxometalate.  相似文献   

20.
The hydrothermal reactions of MoO3, As2O5, Cu(CH3CO2)2 · H2O and an appropriate organonitrogen ligand in the presence of HF as mineralizer yield a series of bimetallic oxides of the Cu/Mo/O/As system. The compounds [{Cu2(4,7-phen)(4,7-phenH)2}Mo12AsO40] · 2.66H2O (1 · 2.66H2O) and [{Cu3(qtpyr)2}Mo12AsO40] · 0.4H2O (2 · 0.4H2O) (qtpyr = 2,4′:5′, 3″:4″,2?-quaterpyridine) are two-dimensional phases constructed from Keggin clusters linked through binuclear {Cu2(4,7-phen)(4,7-Hphen)2}2+ units in metal organic networks in 2. In contrast, the structure of [{Cu2(2,4′-Hbpy)4}Mo18As2O62] · 2H2O (3 · 2H2O) is one-dimensional, consisting of Dawson clusters linked through binuclear {Cu2(Hbpy)4}6+ subunits. In the case of the compounds [{Cu(5,5′-dimethyl-2,2′-bpy)}2Mo2O4F2(AsO4)2] (4) and [{Cu(phen)}2Mo2O4F2(AsO4)2] (5), the fluoride mineralizer has been incorporated into the structure to give one-dimensional phases constructed from oxyfluoride {Mo2O4F2(AsO4)2}2−clusters bridged through {Cu(organonitrogen)}2+ units.  相似文献   

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