Lin Xu

A ferric molybdenum phosphate with a tunnel: hydrothermal synthesis and structure of (NH3CH2CH2NH3)2· (NH3CH2CH2NH2)3·Na·[Fe2Mo12O30(PO4) (HPO4)4(H2PO4)3] · 7H2O

Abstract A new ferric molybdenum phosphate containing a tunnel structure and crystallographically different clusters has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. A probe reaction of the oxidation of acetaldehyde with H2O2 using the title compound as catalyst was carried out in a liquid-solid system, showing that the title compound had high catalytic activity in the reaction.

Synthesis and structural characterization of a new supermolecular compound: H 3 PW 12 O 40 ·6C 14 H 20 O 5 ·16H 2 O (C 14 H 20 O 5 =benzo-15-crown-5)

Abstract The new supermolecular compound, H3PW12O40·6C40H20O5·16H2O (C14H20O5=benzo-15-crown-5), was synthesized in methanol solution and structurally characterized by elemental analysis, IR, 1H NMR and single crystal X-ray diffraction. It was shown that PW12O403− anions possess α-Keggin structure with crystallographic disorder. The disorder averages the W–W distances and W–Ob/c–W angles, but the vibrational ellipsoids of oxygen atoms are not elongated obviously. In the compound, water blocks are formed, which are hydrogen-bonded to crown ether molecules. Since crown ether molecules fetter the movement of water molecules and oxonium ions, the conductivity is lower (ρ r.t. −7 S cm −1 ). The compound crystallizes in the triclinic space group P 1 with a=14.154(3), b=15.598(3), c=18.023(3) A , α=67.17(3), β=89.83(3), γ=83.27(3)°, V=3638.1(13) A 3 , Z=1 and R1(wR2)=0.0655(0.1701).

A molecule based on polyoxometalate acid and crown ether: synthesis and characterization of [(H3O)(C20H24O6)]2[HPMo12O40]·C20H24O6·3MeCN·H2O (C20H24O6=dibenzo-18-crown-6)

Abstract The new molecule based on 12-molybdophosphate acid and dibenzo-18-crown-6, [(H 3 O)(C 20 H 24 O 6 )] 2 [HPMo 12 O 40 ]·C 20 H 24 O 6 ·3MeCN·H 2 O 1 , was synthesized in acetonitrile and characterized by elemental analyses, IR, 1 H NMR, electrospray mass spectra and single crystal X-ray diffraction, indicating that it contains [(H 3 O)(dibenzo-18-crown-6)] + cations, where oxonium ions are out of the planes defined by crown ether oxygen atoms, and disordered PMo 12 O 40 3− anions with α-Keggin structure where the crystal has high lattice energy so that it is difficult to dissolve it. The crystallographic disorder averages Mo–Mo distances and Mo–O b / c –Mo angles between the M 3 triplets and within the M 3 triplet. The interactions between crown ether molecules and oxonium ions are hydrogen-bonding with the O(crown ether)–OH 3 + distances of 2.510(10)–2.783(7)xa0A. The interactions between [(H 3 O)(dibenzo-18-crown-6)] + cations and PMo 12 O 40 3− anions are dominantly electrostatic. The electrical conductivity is −7 xa0S.cm −1 .

Oxidative catalysis of Keggin anion [XW11O39Z(H2O)]n− pillared clays in the reaction of acetaldehyde with H2O2

Abstract In aqueous solution, the layered double hydroxides (LDHs) pillared by heteropolyanions, Co 2 Al–XW 11 Z and Ni 2 Al–XW 11 Z (X=B 3+ , Si 4+ , Ge 4+ and As 5+ ; Z=Cu 2+ , Co 2+ and Ni 2+ ), have been synthesized by the direct ion exchange reaction of the monosubstituted Keggin-type heteropolyanion containing transitional element with the Co 2 Al–NO 3 and Ni 2 Al–CO 3 precursors. The results of XRD and FTIR measurements indicate that they are the pillared layered compounds with gallery height of 0.99±0.01 nm and that Keggin-type framework of the heteropolyanion still remain inside the layers. The composition and properties of these compounds have been evidenced by TG and ICP analyses. The catalytic feature of these pillared layered clays for the oxidative reaction of acetaldehyde with H 2 O 2 has been studied. The formation rate of the product acetic acid was between 20–53 mmol (g-cat.) −1 h −1 and the selectivity for acetic acid was nearly 100%, showing that they were excellent oxidative catalysts in liquid–solid system. In addition, if the catalytic activities are expressed as per mmole of heteropolyanion instead of per gram of the catalyst, the catalytic activities of Co 2 Al–XW 11 Z and Ni 2 Al–XW 11 Z were between three times and nine times that of XW 11 Z as potassium salts in homogeneous system. This may be because the clay layer has a significant effect on the heteropolyanions against decomposition resulting from H 2 O 2 . Furthermore, the composition of the layer and heteropolyanion also influences on the catalytic activity. The experimental results of catalytic activity for the two kinds of clay catalysts of Co 2 Al–SiW 11 Cu and Co 2 Al–NO 3 calcined at different temperatures show that not only the pillared layered structure makes a contribution to the catalytic activity but also the thermo-decomposition product of them, a complex oxide with spinel structure, is a fine catalyst for the oxidation of acetaldehyde into acetic acid.

Synthesis and X-ray structure of [(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40].2C14H20O5 (C14H20O5 = benzo-15-crown-5; Me2NH = dimethylamine)

Abstract[(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40] · 2C14H20O51 was synthesized from benzo-15-crown-5 and H3PMo12O40·24H2O in N,N′-dimethylformamide for the first time. 1 crystallizes in the monoclinic space group C2/c with a = 18.583(4), b = 25.510(5), c = 19.904(4) Å, β = 94.66(3)° Dc = 2.124 mg/m3 for Z = 4. Refinement based on 7358 observed reflections led to a R1(wR2) = 0.0378(0.0761). The complex cation, [(H3O)(C14H20O5)2]+, exhibits a sandwich structure by hydrogen-bonding in the mean distance of 2.955 Å. The anion, PMo12O403−, is a α-Keggin structure.

Chains of (4,4′-bipyridyl)copper(I) bridged by dimolybdate units

The crystal structure of the title compound, polyxad[bis-[copper(I)-μ-(4,4′-bipyridyl)-N:N′]-μ-dimolybdato-O:O′],[Cu2(C10H8N2)2{Mo2O7}]n, consists of {Mo2O7}2− units (with the central O atom lying on twofold symmetry axes) and [Cu(4,4′-bipy)]nn+ chains (bipy = bipyridyl); the chains are generated by a c-glide-plane operation. The {Mo2O7}2− units are covalently bridged to two [Cu(4,4′-bipy)]nn+ chains, forming a complex with a bridged double-chain structure. The Cu—O and Cu—N distances are 2.191u2005(3) and 1.933u2005(3)u2005A, respectively.

A hydrated ethyl­ene­di­ammonium salt of a new polymeric polyoxoanion: (H2en)4[Co(H2O)2(OH)2(VO)6(HPO4)4(PO4)4]·3H2O

The title compound, tetrakisxad(ethylxadenedixadammonium) tetra-μ-hydrogenphosphato-di-μ-hydroxadxo- tetra-μ-phosphato-bisxad(aquaxadcobalt)xadhexakisxad(oxovanadium) trihydrate, was synthesized hydroxadthermally at moderate temperature. The structure consists of diprotonated ethylxadenedixadammonium cations and layers of the polyanions. The polyanion contains four PO4 tetrahedra and three VO5 square pyramids that are linked through corner-sharing by alternating P—O—V, which gives rise to a chain. The chains, connected by CoO4(H2O)2 octahedra, form layers, resulting in a two-dimensional layered structure. The Co—O distances are in the range 1.984u2005(3)–2.038u2005(4)u2005A, the P—O distances 1.508u2005(3)–1.575u2005(3)u2005A and the V—O distances 1.585u2005(3)–2.010u2005(3)u2005A.

Syntheses and lyotropic liquid crystal properties of a series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30

A series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30, Na16[As4W30M4(H2O)2O112].XH2O (M = Zn, Cu, Co, Ni, Mn and Cd), have been synthesized for the first time and structurally characterized by elemental analysis, IR and183W NMR spectra. The crystal structure of Na16[As4W30Cu4(H2O)2O112] · 63H2O was determined to be a triclinic system, of P1 symmetry,a = 1.272 l(3) nm,b = 2.451 6(5) nm,c = 2.6.15 0(5) nm, α = 89.90(3)∘, β =77.32(3)∘, γ = 89.96(3)∘,Z = 2. Using tetrahepty lammonium bromide as a phase transfer reagent, [As4W30Cu4(H2O)2O112]16™was transferred from aqueous solution to organic phase (benzene), and the heteropolyanion lost the coordination water molecules to form the coordination-unsaturated ion. After lactic acid was added to the benzene solution, the coordination-saturation was recovered. By esterification reaction between lactic acid and cholesterin, the latter was attached to the heteropolyanion indirectly. Therefore, a new type of lyotropic liquid crystal was obtained, which was characterized by a polarimicroscope, DSC and variable temperature wide-angle X-ray diffraction.

Magnetic properties of heteropolyoxometalates

The progress of the study on the magnetic properties of heteropolyoxometalates during the late decade is reviewed. Some anions of heteropolyoxometalates containing magnetic atoms, such as [M4(H2O)4(PW9O34)210− and [M4(H2O)4(P2W15O56)216− [M = Co(II), Zn(II), CU(II), Mn(II), Ni(II)], and [GaW9O37M3 (H2O)3]n− [M = Fe(III), CU(II), CO(II)], showed ferromagnetic and antiferrmagnetic properties. The combination of heteropoly anions and organic π-donor of TTF+ (tetrathiofulvalene cation) results in a variety of magnetic properties. Furthermore, there is an interaction between the inorganic and organic components. The electrocrystallization technique can prepare the organic-inorganic salts of this kind, which will become the new member of molecular magnetic materials. Heteropoly blue is a kind of the mixed-valence complexes and its reduction electrons can be delocalized over anionic framework. The further study on the magnetic properties of heteropolyoxometalates will provide important information for the design of molecular materials.