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1.
A theoretical analysis of the temperature-dependent (31)P NMR signals for the ambient pressure vanadyl pyrophosphate AP-(VO)(2)P(2)O(7) and the oxovanadium hemihydrate hydrogenophosphate VO(HPO(4)).0.5H(2)O phases is reported. The ab initio calculation of the magnetic exchange parameters and the hyperfine constants gives access to an original ab initio simulation of NMR spectra. Such a strategy allows one to clarify the crystallographic nature of the different experimentally studied phases. For the vanadyl pyrophosphate ambient pressure structure, our simulations strongly support the presence of a monoclinic phase. Based on this assumption, hyperfine constants are extracted from the fit of the experimental data. These values are directly compared to the ab initio ones.  相似文献   

2.
Large transparent blue crystals of vanadyl pyrophosphate, (VO)(2)P(2)O(7), were grown from a phosphorus pentoxide flux, and the single-crystal X-ray structure of (VO)(2)P(2)O(7) was determined with high precision. On the basis of spin dimer analysis, we examined the spin exchange interactions of (VO)(2)P(2)O(7) and its precursor VO(HPO(4)).0.5H(2)O. Our analysis of (VO)(2)P(2)O(7) using two high-precision crystal structures shows unambiguously that the V3-V4 chain has a larger spin gap than does the V1-V2 chain and that the super-superexchange (V-O...O-V) interaction is stronger than the superexchange (V-O-V) interaction in the V3-V4 chain while the opposite is true in the V1-V2 chain. Our analysis of VO(HPO(4)).0.5H(2)O reveals that the superexchange interaction must dominate over the super-superexchange interaction, in disagreement with the conclusion from a powder neutron scattering study of VO(DPO(4)).0.5D(2)O.  相似文献   

3.
The 1/2V2O5-H2C2O4/H3PO4/NH4OH system was investigated using hydrothermal techniques. Four new phases, (NH4)VOPO(4).1.5H2O (1), (NH4)0.5VOPO(4).1.5H2O (2), (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2]2.3H2O (3), and (NH4)2[VO(HPO4)]2(C2O4).H2O (4), have been prepared and structurally characterized. Compounds 1 and 2 have layered structures closely related to VOPO(4).2H2O and A0.5VOPO4.yH2O (A = mono- or divalent metals), whereas 3 has a 3D open-framework structure. Compound 4 has a layered structure and contains both oxalate and phosphate anions coordinated to vanadium cations. Crystal data: (NH4)VOPO(4).1.5H2O, tetragonal (I), space group I4/mmm (No. 139), a = 6.3160(5) A, c = 13.540(2) A, Z = 4; (NH4)0.5VOPO(4).1.5H2O, monoclinic, space group P2(1)/m (No. 11), a = 6.9669(6) A, b = 17.663(2) A, c = 8.9304(8) A, beta = 105.347(1) degrees, Z = 8; (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2]2.3H2O, triclinic, space group P1 (No. 2), a = 10.2523(9) A, b = 12.263(1) A, c = 12.362(1) A, alpha = 69.041(2) degrees, beta = 65.653(2) degrees, gamma = 87.789(2) degrees, Z = 2; (NH4)2[VO(HPO4)]2(C2O4).5H2O, monoclinic (C), space group C2/m (No. 12), a = 17.735(2) A, b = 6.4180(6) A, c = 22.839(2) A, beta = 102.017(2) degrees, Z = 6.  相似文献   

4.
The vanadyl oxalatophosphate Na2[(VO)2(HPO4)2C2O4].2H2O has been synthesized by hydrothermal treatment. Its structure has been determined and refined by combining X-ray powder diffraction and solid-state NMR techniques. It crystallizes with monoclinic symmetry in space group P2(1), a = 6.3534(1) A, b = 17.1614(3) A, c = 6.5632(1) A, beta = 106.597(1) degrees . The structure is related to that of (NH4)2[(VO)2(HPO4)2C2O4].5H2O, which was previously reported. The vanadium phosphate framework consists of infinite [(VO)(HPO4)] chains of corner-sharing vanadium octahedra and hydrogenophosphate tetrahedra. The oxalate groups ensure the connection between the chains to form a 2D structure. The sodium ions and the water molecules are located between the anionic [(VO)2(HPO4)2C2O4]2- layers. The thermal decomposition has been studied in situ by temperature-dependent X-ray diffraction and thermogravimetry. It takes place in three stages, where the first two correspond to water removal and the last to the decomposition of the oxalate group and water elimination, leading to the final product NaVOPO4.  相似文献   

5.
在具有开放骨架结构的过渡金属磷酸盐微孔材料的合成中,钒磷酸盐因在催化和磁学方面具有潜在的性质和特殊结构特征而引起人们的广泛兴趣.近年来,人们正在尝试用假四面体结构的[HPO3]^2-替代四面体结构的[PO4]^3-,因为{HPO3}结构基元同钒原子的连接方式与{PO4}结构基元和钒原子的连接方式具有明显的差别,  相似文献   

6.
Li CY  Hsieh CY  Lin HM  Kao HM  Lii KH 《Inorganic chemistry》2002,41(16):4206-4210
A new vanadium(IV) silicate, Rb(2)(VO)(Si(4)O(10)).xH(2)O (x approximately 0.1), has been synthesized by a high-temperature, high-pressure hydrothermal method. It crystallizes in the tetragonal space group I4(1)md (No. 109) with a = 12.2225(7) A, c = 7.7948(6) A, and Z = 4. The structure consists of spiral chains of corner-sharing SiO(4) tetrahedra linked to neighboring chains via corner sharing to form a 3-D silicate framework which delimits channels to accommodate the VO(2+) groups. The Rb(+) ions are located in the cavities within the silicate framework. Magnetic susceptibility confirms the valence of vanadium. A partially occupied lattice water site is confirmed by IR and solid state (1)H NMR spectroscopy. The structure of the title compound is considerably different from those of the synthetic silicate K(2)(VO)(Si(4)O(10)).H(2)O and the two polymorphs of the natural mineral Ca(VO)(Si(4)O(10)).4H(2)O, although they have identical framework stoichiometry.  相似文献   

7.
A detailed study of the quaternary aqueous H+/H2VO4-/H2O2/picolinate (Pi-) system has been performed at 25 degrees C in 0.150 M Na(Cl) medium using quantitative 51 V NMR (500 MHz) and potentiometric data (glass electrode). In the ternary H+/H2VO4-/Pi- system, six complexes have been found in the pH region 1-10. In the quaternary H+/H2VO4-/H2O2/Pi- system, eight additional complexes have been found. Generally, equilibria are fast in both systems. The rate of peroxide decomposition depends on the species in solution. Chemical shifts, compositions and formation constants for the species are given. Equilibrium conditions and the fit of the model to the experimental data are illustrated in distribution diagrams. Possible formation of mixed ligand species with imidazole, lactic acid and citric acid have been investigated and ruled out under the same experimental conditions. Structural proposals are given, based on 1)C NMR data and available crystal structures.  相似文献   

8.
The speciation in the aqueous H(+)/H(2)VO(4)(-)/H(2)O(2)/maltol (Ma), H(+)/H(2)VO(4)(-)/uridine (Ur) and H(+)/H(2)VO(4)(-)/H(2)O(2)/Ur systems was determined in the physiological medium of 0.150 M Na(Cl) at 25 degrees C. A combination of quantitative (51)V NMR (Bruker AMX500) and potentiometric data (glass electrode) was collected and treated simultaneously by the computer program LAKE. In the quaternary maltol system, the two species VXMa(2)(-) and VX(2)Ma(2-) (where X denotes the peroxo ligand) were found in the pH region 5-10, in addition to all binary and ternary complexes. Their formation was fast. In the ternary uridine (H(+)/H(2)VO(4)(-)/Ur) subsystem, altogether three vanadate-uridine (V-Ur) species were found in the pH region 4-10, with compositions VUr(2-), V(2)Ur(2)(2-) and V(2)Ur(2)(3-). Equilibrium was fast except in weakly acidic solutions when slowly decomposing decavanadates formed. In the quaternary H(+)/H(2)VO(4)(-)/H(2)O(2)/Ur system, five additional species were found at pH > 7. They were of VXUr and VX(2)Ur compositions. Their formation was fast. Formation constants, compositions and (51)V NMR chemical shifts are given for all the species found in the systems, and equilibrium conditions are illustrated in distribution diagrams as well as the fit of the model to the experimental data. Biological and medical relevance of the species (in the treatment of diabetes) are also discussed, with pseudo-physiological conditions modelled.  相似文献   

9.
The magnetic exchange constants of vanadyl pyrophosphate (VO)(2)P(2)O(7) have been calculated on the basis of a combined DFT/broken symmetry approach. The three reported phases, ambient-pressure orthorhombic, ambient-pressure monoclinic, and high-pressure orthorhombic, have been explicitly considered. Calculations have been performed on four types of model clusters extracted from the crystal lattices. The singularity of each phase is clearly reflected through the number and values of exchange parameters. Our results show that the exchange interactions can be described in first approximation within the alternating antiferromagnetic chain model. The largest exchange coupling along the chain occurs through O-P-O bridges. The interchain interactions are much weaker and are of ferromagnetic nature.  相似文献   

10.
A new series of oxovanadium(IV)-lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)](3)21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)} 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)}8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)](1.5)} 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H(6)TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2- unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2- ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2- ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2- ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)-lanthanide(III) coordination polymers and thus enlarge the realm of 3d-4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.  相似文献   

11.
Single crystals of three new layered uranium phosphate fluorides, A(UO2)F(HPO4).xH2O (A = Cs+, Rb+, and K+; x = 0-1) have been synthesized by hydrothermal reactions using UO3, H3PO4, HF, and corresponding alkali metal halides as reagents. Although all three new materials have layered structures, each of them contains different structural motifs within the layer. While Cs(UO2)F(HPO4).0.5H2O and Rb(UO2)F(HPO4) reveal noncentrosymmetric crystal structures, K(UO2)F(HPO4).H2O crystallizes in a centrosymmetric space group. In addition, the ion-exchanged phases for all three materials are highly crystalline. Crystal data: Cs(UO2)F(HPO4).0.5H2O, orthorhombic, space group Pca21 (No. 29), with a = 25.656(5) A, b = 6.0394(12) A, c = 9.2072(18) A, and Z = 4; Rb(UO2)F(HPO4), orthorhombic, space group Cmc21 (No. 36), with a = 17.719(4) A, b = 6.8771(14) A, c = 12.139(2) A, and Z = 8; K(UO2)F(HPO4).H2O, monoclinic, P21/n (No. 14), with a = 6.7885(14) A, b = 8.7024(17) A, c = 12.020(2) A, beta = 94.09(3), and Z = 4.  相似文献   

12.
Seven new cobalt(II) phosphites, [Co(HPO(3))(C(14)H(14)N(4))(H(2)O)(2)].2H(2)O (1), [Co(HPO(3))(C(22)H(18)N(4))].H(2)O (2), [Co(2)(HPO(3))(2)(C(22)H(18)N(4))(2)H(2)O].H(2)O (3), [Co(2)(HPO(3))(2)(C(12)H(10)N(4))(1.5)H(2)O].1.5H(2)O (4), [Co(HPO(3))(C(14)H(14)N(4))(0.5)].H(2)O (5), [Co(HPO(3))(C(18)H(16)N(4))(0.5)] (6), and [Co(HPO(3))(C(18)H(16)N(4))(0.5)] (7) were synthesized in the presence of 1,2-bis(imidazol-1-ylmethyl)benzene (L1), 1,4-bis(benzimidazol-1-ylmethyl)benzene (L2), 1,3-bis(benzimidazol-1-ylmethyl)benzene (L3), 1,4-bis(1-imidazolyl)benzene (L4), 1,4-bis(imidazol-1-ylmethyl)benzene (L5), 1,4-bis(imidazol-1-ylmethyl)naphthalene (L6), and 1,5-bis(imidazol-1-ylmethyl)naphthalene (L7), respectively, and their structures were determined by X-ray crystallography. Compound 1 is a molecular compound in which two cobalt(II) ions are held together by double mu-O linkages. The inorganic framework of compounds 2 and 3 are composed of vertex-shared CoO(2)N(2)/CoO(3)N(2) and HPO(3) polyhedra that form four rings; these are further linked by an organic ligand to generate 2D sheets. Compounds 4 and 5 both have 1D inorganic structures, with the bifunctional ligands connected to each side of the ladder by coordination bonds to give 2D hybrid sheets. A 3D organically pillared hybrid framework is observed in 6 and 7. In 6, the stacking of the interlayer pillars gives rise to a small hydrophobic channel that extends through the entire structure parallel to the sheets. The temperature-dependent magnetic susceptibility measurements of these compounds show weak interactions between the metal centers, mediated through the mu-O and/or O-P-O linkages.  相似文献   

13.
The ion conductivity of zirconium hydrogen monothiophosphate (Zr(HPO(3)S)(2)x1.5H(2)O) has been measured by impedance spectroscopy. The measured value of proton conductivity is 3 x 10(-5) S/cm at 298 K. Conductivity was shown to decrease with increasing temperature due to a dehydration process. Above 450 K, the conductivity is likely governed by proton transport in the anhydrous phase Zr(HPO(3)S)(2). The activation energies of proton conductivity were measured to be 18 +/- 2 kJ/mol for Zr(HPO(3)S)(2)x1.5H(2)O and 60 +/- 3 kJ/mol for the anhydrous compound. The kinetics of ion exchange was studied with the use of potentiometric titration for several ion pairs, H(+)/Na(+), H(+)/Zn(2+), and Na(+)/Zn(2+) in Zr(HPO(3)S)(2)x1.5H(2)O. The diffusion coefficient values for H(+)/Na(+) ion exchange in Zr(HPO(3)S)(2)x1.5H(2)O are lower than those reported in alpha-zirconium phosphate. At the same time, the mobility of zinc ions in Zr(HPO(3)S)(2)x1.5H(2)O is higher than sodium ion mobility. The ion exchange H(+)/Zn(2+) is accompanied by the slow hydrolysis of the initial compound. In all cases, the powdered solids were evaluated by powder X-ray diffraction, and particle sizes were controlled by grinding and sieving the powders.  相似文献   

14.
Hanson GR  Sun Y  Orvig C 《Inorganic chemistry》1996,35(22):6507-6512
Bis(maltolato)oxovanadium(IV) (abbreviated BMOV or VO(ma)(2)) has been characterized by electron paramagnetic resonance (EPR) spectroscopy in CH(2)Cl(2), H(2)O, MeOH, and pyridine at both room and low temperatures. Spin Hamiltonian parameters for mono- and bis(maltolato)oxovanadium(IV) complexes [VO(ma)](+) (=[VO(ma)(H(2)O)(n)()](+), n = 2 or 3) and VO(ma)(2) (Hma = 3-hydroxy-2-methyl-4-pyrone, maltol) have been obtained by computer simulation (SOPHE). Configurations of solvated vanadyl/maltol complexes, VO(ma)(2)S, in solution (S = solvent) are proposed on the basis of a comparison of their hyperfine coupling constants with those obtained for related vanadium(IV) compounds in the literature. Whereas at room temperature pyridine coordinates to VO(ma)(2) in a position cis to the oxo ligand (cis isomer), in H(2)O or in MeOH solvated and unsolvated cis and trans adducts of VO(ma)(2) are all formed, with the cis isomer dominant. As expected, the coordinating ability was found to be in the order py > H(2)O approximately MeOH > CH(2)Cl(2). In aqueous solutions at room temperature and neutral pH, cis- and trans-VO(ma)(2)(H(2)O) complexes are present as major and minor components, respectively.  相似文献   

15.
The aqueous solution and solid state properties of (4-hydroxypyridine-2,6-dicarboxylato)dioxovanadate(V) (also referred to as (4-hydroxydipicolinato)dioxovanadate(V) or (chelidamato)dioxovanadate(V) and abbreviated [VO(2)(dipic-OH)](-)) were investigated. By using (1)H, (13)C, (17)O, and (51)V NMR 1D and 2D spectroscopy, the species present in solution, together with pK(a) values, equilibrium constants, and labilities, were characterized. The complex is most stable at acidic pH down to pH 1 where it is protonated. The stability of this complex is higher than that of the parent dipicolinatodioxovanadate(V) complex. The dipic-OH ligand is coordinated in a tridentate manner throughout the pH range studied, and the vanadium(V) atom is five-coordinate. Solid state structures of (NMe(4))[VO(2)(dipic-OH)].H(2)O (monoclinic, P2(1)/n) and Na[VO(2)(dipic-OH)].2H(2)O (triclinic, P1) were determined. The discrete complex anions in (NMe(4))[VO(2)(dipic-OH)].H(2)O are connected by hydrogen bonding between the hydroxyl group, a water molecule, and a carboxylate oxygen atom. Changing the counterion from NMe(4)(+) to sodium ion in Na[VO(2)(dipic-OH)].2H(2)O leads to the formation of a polymeric structure. Dynamic processes in solution were explored by using (1)H and (13)C EXSY NMR spectroscopy; exchange between complex and free ligand below pH 4 was observed. The differences between the dipicolinatodioxovanadate(V) parent complex and the [VO(2)(dipic-OH)](-) complex in the solid state and in solution demonstrate the subtle consequences of the one substitutional difference between the two ligands. The insulin-mimetic properties of this compound are likely to be of mechanistic interest in developing an understanding of the mode of action of the few known insulin-mimetic vanadium(V) complexes.  相似文献   

16.
The hydrothermal reactions of MCl(2).6H2O (M = Co, Ni) NaVO3, 4,4'-dipyridylamine (dpa), and H2O yield materials of the type [M(Hdpa)2V4O12] (M = Co (1), Ni (2)). The two-dimensional structures of 1 and 2 are constructed from bimetallic oxide networks (MV4O12)n2n- with monodentate Hdpa projecting the protonated ring into the interlamellar region. The oxide network may be described as ruffled chains of corner-sharing (VO4) tetrahedra linked by (NiO4N2) octahedra into the two-dimensional assembly. Crystal data: C10H10Co0.5N3O6V2(1), monoclinic P2(1)/c, a = 10.388(1) A, b = 7.6749(7) A, c = 16.702(2) A, beta = 102.516(1) degrees, Z = 4. C10H10N3Ni0.5O6V2 (2), monoclinic, P2(1)/c, c = 10.3815(2) A, b = 7.7044(2) A, c = 16.6638(4) A, beta = 102.573(1) degrees, Z = 4.  相似文献   

17.
Th(2)(PO(4))(2)(HPO(4)).H(2)O was synthesized under wet hydrothermal conditions starting from a mixture of H(3)PO(3) and Th(NO(3))(4).5H(2)O. The crystal structure was solved by powder X-ray diffraction data. The unit cell parameters are a = 6.7023(8) Angstroms, b = 7.0150(8) Angstroms, c = 11.184(1) Angstroms, beta = 107.242(4) degrees, space group P2(1), and Z = 2. The structure consists of layers of both thorium atoms and PO(4) groups, alternating with a layer formed by HPO(4) entities and water molecules. By thermal treatment, this compound turns into Th(4)(PO(4))(4)P(2)O(7), a ceramic already described in the field of the immobilization of tetravalent actinides.  相似文献   

18.
1 INTRODUCTION Current research interest is focused on the designof structures built up from octahedral and tetrahedralbuilding blocks[1]. During the wide investigations intransition-metal phosphates for many years, a num-ber of new mixed transition-metal phosphates havebeen reported[2]. A great number of manganese phos-phates were largely discovered as minerals[1]. On theother hand, many vanadium phosphates have alsobeen prepared recently partly because of their poten-tial applications …  相似文献   

19.
Guo M  Yu J  Li J  Li Y  Xu R 《Inorganic chemistry》2006,45(8):3281-3286
The first two low-dimensional beryllium phosphates, [C5H14N2]2[Be3(HPO4)5].H2O (BePO-CJ29) and [C6H18N2]0.5[Be2(PO4)(HPO4)OH].0.5 H2O (BePO-CJ30), have been successfully synthesized under mild hydrothermal/solvothermal conditions. BePO-CJ29 is built up from strict alternation of BeO4 and HPO4 tetrahedra forming a unique one-dimensional double chains with 12-ring apertures. There are pseudo-10-ring apertures enclosed by two double chains through H-bonds. BePO-CJ29 can also be viewed as a pseudo 2-D layered structure stabilized by strong H-bonds. The diprotonated 2-methylpiperazium cations are located at three positions (i.e., inside the 12-ring aperture, inside the pseudo-10-ring aperture, and in the interlayer of the inorganic pseudo-layers. BePO-CJ30 is constructed by the alternation of Be-centered tetrahedra (including BeO4 and HBeO4) and P-centered tetrahedra (including PO4 and HPO4) resulting in a two-dimensional layered structure parallel to the (0 1 1) direction. The complex layer is composed of coupled 4.8 net sheets. The diprotonated 1,6-hexandiamine cations and water molecules reside in the interlayer regions and interact with the inorganic layers through H-bonds. Crystal data are as follows: [C5H14N2]2[Be3(HPO4)5].H2O (BePO-CJ29), triclinic, P1 (No. 2), a = 8.1000(9) A, b = 8.4841(14) A, c = 19.665(2) A, alpha = 89.683(10) degrees, beta = 78.182(8) degrees, gamma = 87.932(9) degrees, V = 1321.9(3) A3, Z = 2, R1 = 0.0523 (I > 2sigma(I)), and wR2 = 0.1643 (all data); [C6H18N2]0.5[Be2(PO4)(HPO4)OH].0.5 H2O (BePO-CJ30), orthorhombic, Pccn (No. 56), a = 26.01(4) A, b = 8.431(12) A, c = 9.598(13) A, V = 2105(5) A3, Z = 8, R1 = 0.0833 (I > 2sigma(I)), and wR2 = 0.2278 (all data).  相似文献   

20.
以有机分子乙二胺作为模板剂合成了新型磷酸钒孔道化合物(H3NCH2CH2NH3)3^-[(VO)4(PO4)2(HPO4)4,并通过X射线单晶衍射实验进行了结构表征,晶体学数据为:C2/c,a=1.8505(9)nm,b=0.7089(4)nm,c=2.3304(10)nm,β=96.43(3)°,V-3.038(3)nm^3,Z=8,R=0.067,Rw^b=0.1635,该化合物具有非常独特和规整的二维孔道骨架结构,进一步的晶体化学研究表明该化合物为一新的VPO物相。  相似文献   

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