Sur un nouveau Complexe entre l'oxyfluorure d'antimoine et l'oxalate. Structure cristalline de (NH4)4H2(C2O4)3(SbOF) 2 · H2O

On a New Complex of Antimony Oxide Fluoride and Oxalate. Crystal Structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O The crystal structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O has been fixed by X-ray diffraction on single crystal (R = 0.025 for 2124 planes). The antimony atom is complexed by the oxalate anions which are bidendate chelates. Antimony coordination is seven (five oxygen atoms, one fluorine atom, and the lone pair E). Antimony environment is a pentagonal bipyramid, one of the axial positions is occupied by the lone pair, the other one by the fluorine atom.     

Vibrational analysis of Ag3(PO2NH)3, Na3(PO2NH)3 x H2O, Na3(PO2NH)3 x 4H2O,

FT IR and FT Raman spectra of Ag3(PO2NH), (Compound 1), Na3(PO2NH)3 x H2O (Compound II), Na3(PO2NH)3 x 4H2O (Compound III), [C(NH2)3]3(PO2NH)3 x H2O (Compound IV) and (NH4)4(PO2NH)4 x 4H2O (Compound V) are recorded and analyzed on the basis of the anions, cations and water molecules present in each of them. The PO2NH- anion ring in compound I is distorted due to the influence of Ag+ cation. Wide variation in the hydrogen bond lengths in compound III is indicated by the splitting of the v2 and v3 modes of vibration of water molecules. The NH4 ion in compound V occupies lower site symmetry and exhibits hindered rotation in the lattice. The correlations between the symmetric and asymmetric stretching vibrations of P-N-P bridge and the P-N-P bond angle have also been discussed.     

NH4VO3在NH4H2PO4-H2O和(NH4)3PO4-H2O体系中的溶解度

采用等温溶解法测定了偏钒酸铵(NH₄VO₃)在NH₄H₂PO₄-H₂O和(NH₄)₃PO₄-H₂O体系中T = 298.15-328.15 K时的溶解度以及溶液的密度和pH值。结果表明, NH₄VO₃的溶解度随着(NH₄)₃PO₄或NH₄H₂PO₄溶液浓度的增大,先降低后升高,这是由于同离子效应、化学反应平衡及离子活度的共同作用。比较T = 298.15K时, NH₄VO₃分别在NH₄H₂PO₄-H₂O、(NH₄)₂HPO₄-H₂O和(NH₄)₃PO₄-H₂O体系中溶解度,发现在相同的磷酸盐浓度下, NH₄VO₃的溶解度在NH₄H₂PO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在(NH₄)₂HPO₄-H₂O体系中最小。进一步地,在T = 298.15 K和磷酸盐浓度C = 0.5 mol·kg^-1时,结合pH值和反应溶度积常数K_SP等计算三个体系中的平均离子活度系数(γ_±),发现γ_±值在(NH₄)₂HPO₄-H₂O体系中最大,在(NH₄)₃PO₄-H₂O体系中居中,在NH₄H₂PO₄-H₂O体系中最小,与溶解度规律一致。     

Etude de la deshydratation de Ca(H2PO4)2·H2O et de sa reaction avec CaSO4 par ATD-ATG couplees

The dehydration of Ca(H₂PO₄)₂·H₂O was examined with simultaneous DTA and TG. This dehydration permitted clearly the apparation of the following phases: Ca(H₂PO₄)₂·0.5H₂O, Ca(H₂PO₄)₂, Ca₃(HP₂O₇)₂, Ca₂HP₃O₁₀ et Ca(PO₃)₂. The reaction of Ca(H₂PO₄)₂·H₂O and CaSO₄ was also examined with the same technics. It was found that the decomposition of CaSO₄ takes place for relatively low temperature (between 600°C and 800°C).     

(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.     

The First Organically Templated Layered Uranium(IV) Fluorides: (H3N(CH2)3NH3)U2F10⋅2 H2O, (H3N(CH2)4NH3)U2F10⋅3 H2O,and (H3N(CH2)6NH3)U2F10⋅2 H2O

A new series of layered organically templated uranium(IV ) fluorides has been exclusively synthesized under hydrothermal conditions. The unprecedented materials contain [U₂F₁₀]²⁻ anionic layers that are separated by charge balancing cationic templates and occluded water molecules (see structure depicted). The templates can be fully ion-exchanged for a variety of metals (Na⁺, K⁺, and Co²⁺) at room temperature.     

Structure cristalline et conformation en solution aqueuse de la carnosine (β-alanyl-L-histidine)

Carnosine (β-alanyl-L-histidine) is a biologically active molecule involved in muscular metabolism. It crystallises in the C; space group with a = 24.725 Å b = 5,427 Å c = 8,004 Å β = 100,2° (Z = 4)

In the crystal, acid and basic groups are engaged in hydrogen bonds whose strength is evaluated through IR frequencies. Molecular conformation in the solid state is defined by τ₁ = /t-177° τ₂ = −38° φ = −96° ψ = +131° χ₁ = 181° χ₂₁ = 62°

NMR study of carnosine in aqueous solution indicates that rotation about CH₂-CH₂ is free and that the other angles take the following values: Ø −150° or −90° and X₁ = 165° or 315°. Infrared and Raman spectra suggest that τ₂ undergoes small changes when going from crystal to solution while ψ is close to +150°.     

Synthesis and Structure of the First Three‐legged Low‐dimensional Iron Phosphate, [H3N(CH2)3NH2(CH2)2NH2(CH2)3NH3][Fe3F6(HPO4)2(PO4)]·3H2O

A hydrothermal reaction of iron acetylacetonate, phosphoric acid, HF, N, N′‐bis(3‐aminopropyl)ethylenediamine and water at 150 °C gave rise to a new iron phosphate, [H₃N(CH₂)₃NH₂(CH₂)₂NH₂(CH₂)₃NH₃][Fe₃F₆(HPO₄)₂(PO₄)] · 3H₂O ( I ). The structure consists of Fe(1)O₄F₂, Fe(2)O₃F₃ octahedral and P(1)O₃(OH) and P(2)O₄ tetrahedral building units connected through their vertices to form fragments of tancoite‐type units. The tancoite‐type units are linked through the phosphate tetrahedra forming an unusual iron phosphate with a hitherto unknown low‐dimensional structure with three‐iron center.Magnetic studies indicate a complex behavior at low temperature and the high‐temperature data (150 — 300 K) has a Curie‐Weiss behavior. The calculated room temperature magnetic moment is 6 μ_B per Fe atom, and the Neel temperature, T_N = 46K. Crystal data: orthorhombic, space group = I2₁2₁2₁ (no. 24), a = 9.9042(11), b = 12.8865(14), c = 19.783(2)Å, U = 2524.9(5), Z = 4.