The influence of partial substitution of phosphorus by arsenic in monoclinic CsH2PO4. X-ray single crystal,vibrational and phase transitions in the mixed CsH2(PO4)0.72(AsO4)0.28

Partial substitution of P by As, leading to the solid solution CsH₂(PO₄)_1−x(AsO₄)_x, with x=0.28 (abbreviated as CDAP) has been shown. The structural characteristics of the crystals were analyzed by means of X-ray diffraction, which revealed that the new title compound is nearly isomorphous with the monoclinic phase of CsH₂PO₄ (CDP). The structure was solved from 796 independent reflections with R₁=0.0292 and Rw₂=0.0702, refined with 59 parameters. The following results have been obtained: space group P2₁, a=4.9250(4) Å, b=6.4370(3) Å, c=7.9280(6) Å, β=107.316(3)°, V=239.94(3) Å³, Z=2 and ρ_cal=3.349 g cm⁻³. The hydrogen bonds are clearly distinguished in the electron density maps which display distributions corresponding to order of protons. The shorter bond (2.452(4) Å), links the phosphate–arsenate groups into chains running along the b-axis and the longer bond (2.531(3) Å), crosslinks the chains to form (001) layers. The Raman and infrared spectra of CDAP recorded at room temperature in the frequency ranges 15–1200 cm⁻¹ and 400–4000 cm⁻¹, respectively, confirm the presence of PO³⁻₄ and AsO³⁻₄ groups in the crystal. Differential scanning calorimetry traces show three phase transitions at 333, 449 and 490 K in this material, which are characterized by X-ray powder diffraction at high temperature.     

A series of open-framework tin(II) phosphates: A[Sn4(PO4)3] (A=Na,K, NH4)

A new series of isostructural open-framework tin(II) phosphates with general formula A[Sn₄(PO₄)₃], where A=Na, K, NH₄, has been synthesized by hydrothermal methods. The crystal structures of NaSn₄(PO₄)₃ (I) and KSn₄(PO₄)₃ (II) have been solved by single crystal X-ray diffraction methods. Both phases crystallize in the trigonal space group R3c (#161) with Z=6 and cell parameters a=9.5508(13) Å, c=24.083(3) Å for I, and a=9.7124(11) Å, c=24.363(3) Å for II. The structure consists of a negatively charged [Sn₄(PO₄)₃]⁻ framework with channels running parallel to the a- and b-axes where the charge compensating A⁺ cations are located. An interesting feature is that half of the channels are empty due to the specific geometry of the SnO₃ units—the lone electron pair of the tin atoms “protrudes” in these channels thus preventing the insertion of A⁺. The new phases have also been characterized by infrared and thermogravimetric analyses.     

Synthesis,growth, structure and characterization of nickel(II)-doped hexaaquacobalt(II) dipotassium tetrahydrogen tetra-o-phthalate tetrahydrate crystals

Single crystals of K₂[Co_(1−x)Ni_x(H₂O)₆] (C₈H₅O₄)₄·4H₂O (x = 0.25) (PCNHP), a semiorganic black colored transparent crystal of size ∼20 × 13 × 4 mm³, are grown from an aqueous solution of potassium hydrogen phthalate enriched with cobalt chloride and nickel chloride by slow evaporation solution growth technique at room temperature. Structural analysis by single crystal X-ray diffraction reveals that the crystal belongs to monoclinic system with space group P2₁/c and the cell parameters are a = 10.41(3) Å, b = 6.84(2) Å, c = 29.46(9) Å, Z = 4. Incorporation of both Co(II) and Ni(II) into the potassium hydrogen phthalate (KHP) crystal lattice is well confirmed by EDS and chemical tests. Powder XRD profiles indicate the crystallinity and FT-IR studies reveal the vibrational patterns. The UV–vis optical absorption spectrum of PCNHP shows the lower optical cut-off at ∼300 nm and the crystal was transparent in the entire visible region. The crystalline perfection of the grown crystal analysed by high-resolution X-ray diffraction (HRXRD) analysis reveals that the diffraction curve (DC) contains multi-peaks with low angular spread indicating the possibility of low angle structural grain boundaries. Scanning electron microscope (SEM) studies indicate the structure defect centers. The dielectric, thermal and mechanical behaviors of the specimen were also investigated.     

Structural and vibrational study a new potassium lithium dihydrogenphosphate KLi(H2PO4)2

The single crystal of potassium lithium dihydrogenphosphate KLi(H₂PO₄)₂ (notated as KLDP) was synthesized at room temperature and its structure determined by single crystal X-ray diffraction. The compound was found to crystallize in the monoclinic system with space group P2₁/c (No.14) and the following parameters a = 7.5197(6), b = 12.8943(10) and c = 7.3900(6) Å, β = 98.477(3) °, Z = 4. This feature structure consists of LiO₄ tetrahedra linked by corners with H₂PO₄ groups to form infinite layer running along the ab plane. In the interlayer, KO₈ polyhedra form layers parallel to the same plane. In addition, Raman and infrared spectra were measured at room temperature, which confirm the presence of H₂PO₄, LiO₄ groups and ABC bands in the unit cell. In fact, these fundamental vibrations were proposed by analogy with spectra of other phosphate-based hydrogen-bonded compounds.     

Crystal structures of Th(OH)PO4, U(OH)PO4 and Th2O(PO4)2. Condensation mechanism of MIV(OH)PO4 (M = Th,U) into M2O(PO4)2

Three new crystal structures, isotypic with β-Zr₂O(PO₄)₂, have been resolved by the Rietveld method. All crystallize with an orthorhombic cell (S.G.: Cmca) with a = 7.1393(2) Å, b = 9.2641(2) Å, c = 12.5262(4) Å, V = 828.46(4) Å³ and Z = 8 for Th(OH)PO₄; a = 7.0100(2) Å, b = 9.1200(2) Å, c = 12.3665(3) Å, V = 790.60(4) Å³ and Z = 8 for U(OH)PO₄; a = 7.1691(3) Å, b = 9.2388(4) Å, c = 12.8204(7) Å, V = 849.15(7) Å³ and Z = 4 for Th₂O(PO₄)₂. By heating, the M(OH)PO₄ (M = Th, U) compounds condense topotactically into M₂O(PO₄)₂, with a change of the environment of the tetravalent cation that lowers from 8 to 7 oxygen atoms. The lower stability of Th₂O(PO₄)₂ compared to that of U₂O(PO₄)₂ seems to result from this unusual environment for tetravalent thorium.     

The synthesis and crystal structure of a hydrated magnesium phosphate Mg3(PO4)2·4H2O

The synthesis and crystal structure of a novel hydrated magnesium phosphate is described. The crystal structure was solved from powder X-ray diffraction data. Mg₃(PO₄)₂·4H₂O crystallizes in the orthorhombic space group Cmc2₁ (No. 36) with a=8.41087(9) Å, b=17.3850(2) Å, c=12.8034(1) Å, V=1872.15(4) ų and Z=8. The structure consists of sheets stacked along [010], which are linked by edge sharing octahedral Mg₂O₆(H₂O)₄ dimers. Within the sheets there are infinite edge-sharing chains of Mg octahedra along [100]. The compound has been further characterized by ³¹P MAS NMR spectroscopy and thermogravimetric analysis. The crystal structure of two dehydrated variants existing around 200 (Mg₃(PO₄)₂·2.5H₂O) and 275 °C (Mg₃(PO₄)₂·2H₂O) remain unknown.     

Synthesis and structure of Cu3PO4[1,2,4-triazole]2OH with a hybrid layered structure: A new organically templated copper (II) hydroxyphosphate

A new layered copper hydroxyphosphate Cu₃PO₄(1,2,4-triazole)₂OH was synthesized by the mild hydrothermal route and the crystal structure was solved by the single crystal X-ray diffraction method. This compound crystallizes in the monoclinic space group P2₁/a with: a = 10.1456(5) Å, b = 7.8756(4) Å, c = 12.9008(6) Å, β = 111.64(2)°, V = 960.86(8) Å³, Z = 4, D_x = 3.033 g cm^?3. The Cu(II) atoms are embedded in deformed square-pyramidal (Cu1 and Cu3) or octahedral (Cu2) sites made of N and O (or OH) atoms. Both Cu1 and Cu2 polyhedra form dimers connected one to each other, via OH groups, in ribbons which built a bidimensional (001) layer through PO₄ connections. The Cu3 polyhedra built a (001) double-sheet layer through triazol connections. These layers are bridged by triazole and PO₄ groups along the c-direction yielding a lamellar arrangement. Its structural analysis evidences a two-dimensional character for this copper hybrid material which could begin a new series of MOF compounds.     

Mechanochemical synthesis and ionic conductivity of lanthanum phosphosilicate oxyapatites

Lanthanum phosphosilicate apatites with the chemical formula Sr_10–xLa_x(PO₄)_6–x(SiO₄)_xO, where 0 ≤ x ≤ 6, usually prepared by a solid-state reaction at about 1400 °C, were synthesized via the mechanochemical method at room temperature. The samples were characterized using powder X-ray diffraction, infrared spectroscopy and thermal analysis. The results showed that the prepared products were carbonated apatites and no secondary phase was detected. The realization of the milling under a controlled atmosphere can lead to oxyapatites containing no carbonates. The ionic conductivity of the Sr₆La₄(PO₄)₂(SiO₄)₄O sample was investigated by using impedance spectroscopy. The highest ionic conductivity value of 1.522 × 10⁻⁶ S·cm⁻¹ was found at 800 °C. In the investigated temperature range, the activation energy is of 0.85 eV.     

Effect of Ca,Mg-ions on the properties of LiCo0.9M0.1PO4/graphitic carbon composites

LiCo_0.9M_0.1PO₄ (M = Co²⁺, Mg²⁺, Ca²⁺)/graphitic carbon composites are synthesized by Pechini-assisted sol–gel process and annealed by the 2-steps annealing process (300 °C for 5 min in air, then at 730 °C for 12 h in nitrogen). The structural investigation, performed on powders, reveals the presence of LiCoPO₄ as the major crystalline phase and of CoP₂O₇ (M = Co), of Co₂P (M = Mg), of Co₂P, Li₃PO₄, (Ca,Co)₃(PO₄)₂ (M = Ca) as impurities. The morphological investigation of the composites shows the formation of crystalline “islands-like” structures with acicular crystallites with different dimensions (typically 5–50 μm) on the top of them. The voltammetric analysis shows a very good reversibility of the (de)intercalation processes and the presence of two mean peak maxima in the cathodic region at ∼5.01 V and ∼5.05 V respectively. The discharge specific capacities, at a discharge rate of C/10 and room temperature, were 100 mAh g⁻¹ for M = Co, 68 mAh g⁻¹ for M = Mg and 104 mAh g⁻¹ for M = Ca respectively. The electrochemical impedance spectroscopy data reveal a decrease of the electrical resistance and the improvement of the Li-ion conductivity in the Ca and Mg ions containing composites.     

The crystal structure, thermal behaviour and ionic conductivity of a novel lithium gadolinium polyphosphate LiGd(PO3)4

Crystal structure and ionic conductivity of lithium gadolinium polyphosphate, LiGd(PO₃)₄, were investigated. Single crystals of the title compound have been grown by a flux technique. The structure of this novel phosphate was determined by single crystal X-ray diffraction techniques. LiGd(PO₃)₄ is isotypic with LiNd(PO₃)₄. It crystallizes in the monoclinic space group C2/c with the unit cell parameters a=16.386(2), b=7.059(3), c=9.677(2) Å, β=126.12(1)°, V=904.2(4) Å³ and Z=4. The structure refined from 967 independent reflections leads to R₁=0.0167 and wR₂=0.0458. The lattice of LiGd(PO₃)₄ is built of twisted zig-zag chains running along with the b direction and make up of PO₄ tetrahedra sharing two corners, connected to the GdO₈ and LiO₄ polyhedra by common oxygen atoms to form a three-dimensional framework. Differential and thermogravimetric thermal analysis are given. The thermal curve of this compound was recorded and interpreted in agreement with impedance measurements. The ionic conductivity has been measured on pellet of the polycrystalline powder and evaluated as a function of temperature. This phase showed the conductivity of 2×10⁻⁶ and 2×10⁻⁴ Ω⁻¹ cm⁻¹ at 682 and 951 K, respectively.     

New compounds in the cesium sulfobromide rhenium octahedral cluster chemistry: syntheses and crystal structures of Cs4Re6S8Br6 and Cs2Re6S8Br4

The exploration of the CsReSBr system, in order to identify new phases based on octahedral cluster anions, has produced single crystals of Cs₄Re₆S₈Br₆ (1) (trigonal, space group P-6c2, a=9.7825 (3) Å, c=18.7843 (5) Å, V=1556.77 (1) ų, Z=2, density=5.09 g cm⁻³, μ=36.07 mm⁻¹) and Cs₂Re₆S₈Br₄ (2) (monoclinic, space group P2₁/n, a=6.3664 (1) Å, b=18.4483 (4) Å, c=9.3094 (2) Å, β=104.2618 (8)°, V=1059.69 (4) ų, Z=2, density=6.14 g cm⁻³, μ=45.83 mm⁻¹). These two compounds have been obtained by high-temperature solid state route. Their structures have been solved and refined from single crystal X-ray diffraction data. The structure of Cs₄Re₆S₈Br₆ presents isolated anionic cluster units inscribed in a (Cs⁺)₁₂ cuboctahedron and the one of Cs₂Re₆S₈Br₄ exhibits ReS^i-a,a-iRe inter-unit bridges. The framework of the latter presents then a strongly 1-D character.     

Structure,infrared and Raman spectroscopic studies of newly synthetic AII(SbV0.50FeIII0.50)(PO4)2 (ABa,Sr, Pb) phosphates with yavapaiite structure

The synthesis and structural study of three new A^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ (ABa, Sr, Pb) phosphates belonging to the ASbFePO system were reported here for the first time. Structures of [Ba], [Sr] and [Pb] compounds, obtained by solid state reaction in air atmosphere, were determined at room temperature from X-ray powder diffraction using the Rietveld method. Ba^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ features the yavapaiite-type structure, with space group C2/m, Z = 2 and a = 8.1568(4) Å; b = 5.1996(3) Å c = 7.8290(4) Å; β = 94.53(1)°. A^II(Sb^V_0.5Fe^III_0.5)(PO₄)₂ (ASr, Pb) compounds have a distorted yavapaiite structure with space group C2/c, Z = 4 and a = 16.5215(2) Å; b = 5.1891(1) Å c = 8.0489(1) Å; β = 115.70(1)° for [Sr]; a = 16.6925(2) Å; b = 5.1832(1) Å c = 8.1215(1) Å; β = 115.03(1)° for [Pb]. Raman and Infrared spectroscopic study was used to obtain further structural information about the nature of bonding in selected compositions.     

Synthesis,structure and NMR characterization of a new monomeric aluminophosphate [dl-Co(en)3]2[Al(HPO4)2(H1.5PO4)2(H2PO4)2](H3PO4)4 containing four different types of monophosphates

A new zero-dimensional (0D) aluminophosphate monomer [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄ (designated AlPO-CJ38) with Al/P ratio of 1/6 has been solvothermally prepared by using racemic cobalt complex dl-Co(en)₃Cl₃ as the template. The Al atom is octahedrally linked to six P atoms via bridging oxygen atoms, forming a unique [Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂]^6? monomer. Notably, there exists intramolecular symmetrical O?H?O bonds, which results in pseudo-4-rings stabilized by the strong H-bonding interactions. The structure is also featured by the existence of four different types of monophosphates that have been confirmed by ³¹P NMR and ¹H NMR spectra. The crystal data are as follows: AlPO-CJ38, [dl-Co(en)₃]₂[Al(HPO₄)₂(H_1.5PO₄)₂(H₂PO₄)₂](H₃PO₄)₄, M = 1476.33, monoclinic, C2/c (No. 15), a = 36.028(7) Å, b = 8.9877(18) Å, c = 16.006(3) Å, β = 100.68(3)°, U = 5093.2(18) Å³_, Z = 4, R₁ = 0.0509 (I > 2σ(I)) and wR₂ = 0.1074 (all data). CCDC number 689491.     

Magnetic properties of hybrid organo-inorganic copper(II) oxovanadate(V) phosphate and phosphonate bridged systems

The hybrid organo-inorganic compounds [Cu₄(bipy)₄V₄O₁₁(PO₄)₂]nH₂O (n ∼ 5) (1), [Cu₂(phen)₂(PO₄)(H₂PO₄)₂(VO₂) · 2H₂O] (2) and [Cu₂(phen)₂(O₃PCH₂PO₃)(V₂O₅) (H₂O)]H₂O (3) which present different bridging forms of the phosphate/phosphonate group, show different bulk magnetic properties. We herein analyze the magnetic behaviour of these compounds in terms of their structural parameters. We also report a theoretical study for compound (1) assuming four different magnetic exchange pathways between the copper centres present in the tetranuclear unit. For compound (1) the following J values were obtained J₁ = +3.29; J₂ = −0.63; J₃ = −2.23; J₄ = −46.14 cm⁻¹. Compound (2) presents a Curie–Weiss behaviour in the whole range of temperature (3–300 K), and compound (3) shows a maximum for the magnetic susceptibility at 64 K, typical for antiferromagnetic interactions. These data where fitted using a model previously reported in the literature, assuming two different magnetic exchange pathways between the four copper(II) centres, with J₁ = −30.0 and J₂ = −8.5 cm⁻¹.     

Synthesis and crystal structure of the synthetic analogue of mineral minyulite K[Al2F(H2O)4(PO4)2]. Structural correlations with AlPO4-CJ2

The validation of our program of simulation for the prediction of unknown dehydrated structures needs accurate information of the mother hydrated structure at the starting point. This paper describes the synthesis (95°C, 10 days, autogenous pressure) and the structure (space group Pba2; a=9.3477(2), b=9.7571(1), c=5.5280(1) Å, V=503.91 Å³, Z=2) of the synthetic homologue of two-dimensional mineral minyulite K[Al₂F(H₂O)₄(PO₄)₂]. The ²⁷Al, ¹⁹F and ³¹P solid state NMR characteristics are reported, as well as the thermal decomposition which confirms the prediction of a collapse of the structure. Finally, structural correlations between minyulite and AlPO₄-CJ2 are given.     

Identification of a new family of phosphate compounds,AIBII6(P2O7)2P3O10: structures of KMn6(P2O7)2P3O10 and AgMn6(P2O7)2P3O10

Two members of a new family of inorganic phosphates of general formula A^IB^II₆(P₂O₇)₂P₃O₁₀; KMn₆(P₂O₇)₂P₃O₁₀ (a=5.405(2), b=26.918(11), c=6.660(5), β=107.31(3)°, V=925.1(9) Å³, space group P2₁/m, Z=2, D_calc=3.481 Mg m⁻³, R=0.0377 for 2235 observed reflections) and AgMn₆(P₂O₇)₂P₃O₁₀ (a=5.424(7), b=26.97(4), c=6.627(9), β=106.81(7)°, V=928(2) Å³, space group P2₁/m, Z=2, D_calc=3.716 Mg m⁻³, R=0.0594 for 1577 observed reflections) have been synthesized and identified by single crystal X-ray diffraction. The isostructural complexes present an interesting comparison of silver and potassium bonding.     

Etude du diagramme d’equilibre du systeme NaPO3−Pr(PO3)3

The NaPO₃?Pr(PO₃)₃ system was studied by microdifferential thermal analysis (DTA), IR and X-ray diffraction spectroscopies. The only new compound observed in the system is NaPr(PO₃)₄, which melts incongruently at 1149 K. A eutectic appears at 5% Pr(PO₃)₃ at 901 K. The new compound NaPr(PO₃)₄ was characterized by means of powder X-ray diffraction and IR absorption spectroscopy. NaPr(PO₃)₄ is a NaLa(PO₃)₄ isotype; it crystallizes in the monoclinic system P2₁/c witha=12.328(7),b=13.130(5),c=7.231(5) Å, β=126°, 18(5),Z=4,V=945 ?³.     

Trapping phosphate anions inside the [Ag4I] framework: Structure, bonding, and properties of Ag4I(PO4)

Orange-red Ag₄I(PO₄) crystallizes in the monoclinic system, space group P2₁/m (No. 11), with the unit cell dimensions a=9.0874(6) Å, b=6.8809(5) Å, c=11.1260(7) Å, β=109.450(1)°, and Z=4. The crystal structure is fully ordered; it comprises the silver-iodine three-dimensional positively charged framework hosting the tetrahedral PO₄³⁻ guest anions. The framework features high coordination numbers for iodine and manifold Ag-Ag bonds ranging from 3.01 to 3.46 Å. The Ag-Ag interaction is bonding, it involves silver 4d and 5s orbitals lying, together with the orbitals of iodine, just below the Fermi level. Though the orbitals of silver and iodine define the conducting properties of the title compound, the interaction between the framework and the guest anions is also important and is responsive to the number of the silver atoms surrounding the PO₄³⁻ tetrahedra. Ag₄I(PO₄) melts incongruently at 591 K and produces a mixture of the silver phosphate and an amorphous phase upon cooling. Pure Ag₄I(PO₄) is a poor conductor with a room temperature conductivity of 3×10⁻⁶ S m⁻¹. The discrepancies between the properties observed here and those reported previously in the literature are discussed.     

Piperazinium dihydrogen phosphate,C4H12N2(H2PO4)2: Synthesis, 31P CP/MAS NMR,structural and thermal investigations

A new piperazinium dihydrogen orthophosphate, C₄H₁₂N₂(H₂PO₄)₂ was discovered and characterized by combining information from X-ray diffraction, ³¹P CP/MAS NMR and thermal analysis (TG/DTA). The compound C₄H₁₂N₂(HPO₄)·H₂O, was also studied in order to compare these two similar materials. The hydrothermal stability is investigated for the system: 1.0 C₄H₁₀N₂: n H₃PO₄: 55–60 H₂O, 0.5 < n < 3. The reaction mixtures with pH in the range 1.6–8.4 were placed at a fixed temperature in the range 20–180 °C for ca. 5 days. C₄H₁₂N₂(H₂PO₄)₂ was obtained when n > ca. 2. A crystal of piperazinium dihydrogen phosphate, C₄H₁₂N₂(H₂PO₄)₂ was structurally investigated using X-ray diffraction: triclinic, space group $P\overline{1}$, a = 7.023(2), b = 7.750(3), c = 12.203(4) Å, α = 84.668(7), β = 81.532(7) and γ = 63.174(6)°, V = 586.0(4) Å³ and Z = 2. The reactivity of C₄H₁₂N₂(H₂PO₄)₂ was investigated by systematic solvothermal syntheses.     

Vibrational study and crystal structure refinement of BaHPO4

X-ray single crystal structure of BaHPO₄ is refined in the centric space group Pbnm (No. 62) with a=4.609(1) Å, b=14.195(3) Å, c=17.214(5) Å, V=1126.3(5) Å³, Z=12 and a final R value of 0.036 for 1261 independent reflections. The atomic arrangement consists of anionic linear chains lying parallel to the a direction and strongly linked by hydrogen bonds. Two successive chains are separated by Ba²⁺ cations. A comparison of the anionic networks for some similar compounds is also given. The polarized Raman and infrared absorption spectra are investigated. A factor group analysis leads to determination of internal modes of the PO₄³⁻ anions. The vibrational study confirmed the strong HOP hydrogen bonds to the phosphate groups and indicated a notable hydrogen bridges in BaHPO₄ compound.