Flux growth of vanadyl pyrophosphate, (VO)(2)P(2)O(7), and spin dimer analysis of the spin exchange interactions of (VO)(2)P(2)O(7) and vanadyl hydrogen phosphate,VO(HPO(4)).0.5H(2)O

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.     

A hydrothermal investigation of the 1/2V2O5-H2C2O4/H3PO4/NH4OH system: synthesis and structures of (NH4)VOPO(4).1.5H2O, (NH4)0.5VOPO(4).1.5H2O, (NH4)2[VO(H2O)3]2[VO(H2O)][VO(PO4)2](2).3H2O, and (NH4)2[VO(HPO4)]2(C2O4).5H2O

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.     

Na2[(VO)2(HPO4)2C2O4].2H2O: crystal structure determination from combined powder diffraction and solid-state NMR

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.     

Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2O

Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs₂V₂O₃(PO₄)(HPO₄), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs₂[(VO)₃(HPO₄)₄(H₂O)]·H₂O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO₆ octahedra and PO₄ tetrahedra. In (I), infinite chains of corner‐sharing VO₆ octahedra are connected to V₂O₁₀ dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V₃O₁₅(H₂O) trimers separated by hydrogenphosphate groups. Both structures show three‐dimensional frameworks with tunnels in which Cs⁺ cations are located.     

Exchange interactions in the three phases of vanadyl pyrophosphate (VO)(2)P(2)O(7)

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.     

Intermolecular interactions of substituents and31P NMR spectra in phosphazo (phosphinimine) compounds

Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 24, No. 1, pp. 20–28, January–February, 1988.     

ChemInform Abstract: Two Caesium Vanadium Hydrogenphosphates,with Tunnelled Structures: Cs2V2O3(PO4)(HPO4) and Cs2 [(VO)3(HPO4)4(H2O)] ·H2O.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

[VO(SeO3)(H2O)2]·0.5H2O

In poly[[diaquaoxido[μ₃‐trioxidoselenato(2−)]vanadium(IV)] hemihydrate], {[VO(SeO₃)(H₂O)₂]·0.5H₂O}_n, the octahedral V(H₂O)₂O₄ and pyramidal SeO₃ building units are linked by V—O—Se bonds to generate ladder‐like chains propagating along the [010] direction. A network of O—H...O hydrogen bonds helps to consolidate the structure. The O atom of the uncoordinated water molecule lies on a crystallographic twofold axis. The title compound has a similar structure to those of the reported phases [VO(OH)(H₂O)(SeO₃)]₄·2H₂O and VO(H₂O)₂(HPO₄)·2H₂O.     

Open-framework Borophosphate:(NH4)0.5FeⅡ0.5FeⅢ0.5·(H2O)2 BP2O8·0.5 H2O

An open-framework ammonium ferricborophosphate compound was synthesized by mild hydrothermal condition at 110°C. The crystal structure has been determined by single-crystal X-ray diffraction analysis: hexagonal, P6522, a = 9.452(2)A, c = 15.698(5)A,α = 90°,γ = 120°,Z= 6, Mr = 310.58, V = 1214.0(5)A3, Dc = 2.549 g/cm3, μ= 2.311mm-1, F(000) = 930. The chiral tetrahedral-tetrahedral helical ribbons are linked by the mixed valance FeII/FeIIIO6 coordinated octahedra. The ammonium ions are located inside the free loop of helical ribbons close to the inner wall of the helical channels{[BP2O8]3-}, effecting on balancing charge and stabilizing helical ribbons.     

Syntheses and structures of two low-dimensional beryllium phosphate compounds: [C5H14N2]2[Be3(HPO4)5].H2O and [C6H18N2]0.5[Be2(PO4)(HPO4)OH].0.5H2O

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).     

Doppelkettenstruktur von (pipzH2)[MnF2(HPO4)(H2O)](H2PO4)

By adding piperazine to a hydrofluoric and phosphoric acid solution of Manganese(III) fluoride, the fluoride phosphate (pipzH₂)[MnF₂(HPO₄)(H₂O)](H₂PO₄) can be crystallized. Its structure is built by piperazinium(2+) cations, (H₂PO₄)^? anions, and an anionic double‐chain of [HPO₄] tetrahedra and [MnO₃F₂(H₂O)] octahedra. The structure is triclinic, space group P , Z = 2, a = 622.97(4), b = 923.46(6), c = 1183.62(7) pm, α = 98.343(6)°, β = 100.747(7)°, γ = 107.642(5)°, R = 0.0289. It is worth noting that a ferrodistortive Jahn‐Teller order is observed with [MnO₃F₂(H₂O)] octahedra strongly elongated along the F–Mn–OH₂ axes perpendicular to the chain plane. The structure is stabilized by very strong hydrogen bonds.     

The 31P NMR spectra of ArCr(CO)2P(C6H5)3 compounds in neutral and acidic media

The ³¹P NMR spectra of C₆H₅XCr(CO)₂P(C₆H₅)₃ (X = H, CH₃, OCH₃, N(CH₃)₂, COOCH₃) (I), p-C₆H₄X₂Cr(CO)₂P(C₆H₅)₃ (X = COOCH₃)(II) and C₆H₃X₃Cr(CO)₂P(C₆H₅)₃ (X = CH₃) (III) complexes in neutral and acidic media were investigated. The protonation of complexes I and III in trifluoroacetic acid results in the greater upfield shielding of ³¹P{¹H} signal. In this case the complexes I (X = H, CH₃, OCH₃) are completely protonated at the metal, complex I (X = COOCH₃)is partially protonated, while no protonation occurs in the case of complex II.Temperature-dependence of the ³¹P{¹H} NMR spectra was investigated for complexes I (X = H, OCH₃) in a 1/10 mixture of trifluoroacetic acid and toluene and for complexes I (X = COOCH₃) and II in trifluoroacetic acid. The degree of protonation was found to increase with decreasing temperature.     

(NH4)3[VO2(SO4)2(H2O)2]·1.5H2O

The title compound, tri­ammonium cis‐di­aqua‐cis‐dioxo‐trans‐disulfatovanadate 1.5‐hydrate, was obtained by oxidizing V^IV to V^V in a 2 M sulfuric acid solution of vanadyl­ sulfate and adding ammonium sulfate. Here, the V atom is sandwiched by two sulfate groups by corner‐sharing to form a discrete [VO₂(SO₄)₂(OH₂)₂]^3? anion. The water mol­ecules occupy cis positions in the equatorial plane of the vanadium octahedron.     

Anion-directed crystallization of coordination polymers: syntheses and characterization of Cu(4)(2-pzc)(4)(H(2)O)(8)(Mo(8)O(26)).2H(2)O and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2-pzc = 2-pyrazinecarboxylate)

Two new copper 2-pyrazinecarboxylate (2-pzc) coordination polymers incorporating [Mo(8)O(26)](4-) and [V(10)O(28)H(4)](2-) anions were synthesized and structurally characterized: Cu(4)(2-pzc)(4))(H(2)O)(8)(Mo(8)O(26)).2H(2)O (1) and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2). Crystal data: 1, monoclinic, space group P2(1)/n, a = 11.1547(5) A, b = 13.4149(6) A, c = 15.9633(7) A, beta = 90.816(1) degrees; 2, triclinic, space group P1, a = 10.5896(10) A, b = 10.7921(10) A, c = 13.5168(13) A, alpha = 104.689(2) degrees, beta = 99.103(2) degrees, gamma = 113.419(2) degrees. Compound 1 contains [Cu(2-pzc)(H(2)O)(2)] chains charge-balanced by [Mo(8)O(26)](4-) anions. In compound 2, layers of [Cu(3)(2-pzc)(4)(H(2)O)(2)] form cavities that are filled with [V(10)O(28)H(4)](2-) anions. The magnetic properties of both compounds are described.     

Structure and spectral characteristics of (NH4)2[Re2(HPO4)4 · 2H2O]

The compound (NH₄)₂[Re₂(HPO₄)₄ · 2H₂O] has been synthesized and characterized by electronic and vibrational spectroscopy. The molecular structure has been determined by X-ray diffraction (MoK _α radiation, λ = 0.71073 Å). The (NH₄)₂[Re₂(HPO₄)₄ · 2H₂O] coordination units form centrosymmetrical binuclear ordering with each metal atom being coordinated in a distorted octahedron incorporating one rhenium atom, one oxygen atom of the water molecule, and four phosphate oxygen atoms in the equatorial plane. The rhenium-rhenium bond length (2.2207 Å) corresponds to a quadruple bond between the atoms. The [Re₂(HPO₄)₄ · 2H₂O]^2- complex anions in the crystal are associated through strong hydrogen bonds formed by the phosphate O-H···O groups. The stability of dirhenium(III) tetra-μ-phosphates in aqueous solutions is considered.     

Synthesis and Characterization of a New Layered Zinc Phosphite (NH4)[{Zn(H2O)4}0.5Zn2(HPO3)3]

A new layered zinc phosphite with the formula (NH₄)[{Zn(H₂O)₄}_0.5Zn₂(HPO₃)₃] has been synthesized under hydrothermal conditions. Its structure was determined by single‐crystal X‐ray diffraction. The compound crystallizes in the triclinic system, space group (No. 2), a = 7.2507(4), b = 9.7982(6), c = 10.2642(6) Å, α = 63.425(2), β = 87.165(2), γ = 72.999(3)°, V = 620.84(6) ų, Z = 2. The connectivity of ZnO₄ tetrahedra, HPO₃ pseudo pyramids and ZnO₂(H₂O)₄ octahedra results in macroanionic layers with 4.8 net.