Synthesis and characterization of a new organic dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2

Chemical preparation, crystal structure, calorimetric studies and spectroscopic investigation are given for a new organic cation dihydrogenomonophosphate [3,5-(CH₃O)₂C₆H₃NH₃]₂(H₂PO₄)₂. This compound is triclinic with the following unit cell parameters: a=9.030(6) Å, b=16.124(5) Å, c=8.868(3) Å, α=75.04(3)°, β=110.71(4)°, γ=104.61(1)°, Z=4, V=1148.0(1) Å³, Z=2 and ρ_cal.=1.454 g cm⁻³. Crystal structure was solved and refined to R=0.04, 2752 independent reflections. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions parallel to planes, between which are located the organic groups. Solid-state and MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups.     

Synthesis and characterization of a new 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate (C4H8N5)2H2P2O7·2H2O

Structural properties of the 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate are discussed on the basis of an X-ray structure investigation. (C₄H₈N₅)₂H₂P₂O₇·2H₂O is monoclinic, C2/c, with a = 10.414(1) Å, b = 13.365(1) Å, c = 13.736(2) Å, β = 98.39(4)°, and Z = 4. The structure has been solved by a direct method and refined to a reliability R factor of 0.0375 (R_w = 0.0961) using 2751 independent reflections. The structural arrangement can be described as inorganic infinite ribbons, , spreading along the c direction; the organic groups, [C₄H₈N₅]⁺, link the precedent ribbons, via their hydrogen bonds, to form a three-dimensional network. The present work, deals with crystal structure, thermal behavior and IR analysis of this new compound.     

Structural characterization and AC conductivity of bis tetrapropylammonium hexachlorado-dicadmate, [N(C3H7)4]2Cd2Cl6

Synthesis, crystal structure, vibrational study, ¹³C, ¹¹¹Cd CP-MAS-NMR analysis and electrical properties of the compound [N(C₃H₇)₄]₂Cd₂Cl₆, are reported. The latter crystallizes in the triclinic system (space group , Z = 2) with the following unit cell dimensions: a = 9.530(1) Å, b = 11.744(1) Å, c = 17.433(1) Å, α = 79.31(1)°, β = 84.00(1)° and γ = 80.32(1)°. Besides, its structure was solved using 6445 independent reflections down to R = 0.037. The atomic arrangement can be described by alternating organic and inorganic layers parallel to the plan, made up of tetrapropylammonium groups and Cd₂Cl₆ dimers, respectively. In crystal structure, the inorganic layer, built up by Cd₂Cl₆ dimers, is connected to the organic ones through van der Waals interaction in order to build cation-anion-cation cohesion. Impedance spectroscopy study, reported in the sample, reveals that the conduction in the material is due to a hopping process. The temperature and frequency dependence of dielectric constants of the single crystal sample has been investigated to determine some related parameters to the dielectric relaxation.     

[NH3(CH2)2NH3][Co(SO4)2(H2O)4]: Chemical preparation, crystal structure, thermal decomposition and magnetic properties

Cobalt ethylenediammonium bis(sulfate) tetrahydrate, [NH₃(CH₂)₂NH₃][Co(SO₄)₂(H₂O)₄], has been synthesised by slow evaporation at room temperature. It crystallises in the triclinic system, space group , with the unit cell parameters: a = 6.8033(2), b = 7.0705(2), c = 7.2192(3) Å, α = 74.909(2)°, β = 72.291(2)°, γ = 79.167(2)°, Z = 1 and V = 317.16(2) Å³. The Co(II) atom is octahedrally coordinated by four water molecules and two sulfate tetrahedra leading to trimeric units [Co(SO₄)₂(H₂O)₄]. These units are linked to each other and to the ethylenediammonium cations through OW-H…O and N-H…O hydrogen bonds, respectively. The zero-dimensional structure is described as an alternation between cationic and anionic layers along the crystallographic b-axis. The dehydration of the precursor proceeds through three stages leading to crystalline intermediary hydrate phases and an anhydrous compound. The magnetic measurements show that the title compound is predominantly paramagnetic with weak antiferromagnetic interactions.     

Synthesis and characterization of a new organic dihydrogen phosphate-arsenate: [H2(C4H10N2)][H2(As, P)O4]2

Chemical preparation, crystal structure, calorimetric and spectroscopic investigations (IR and RMN) are given for a new non-centrosymmetric organic-cation dihydrogen phosphate-arsenate [H₂(C₄H₁₀N₂)][H₂(As, P)O₄]₂. This compound is triclinic P1 with the following unit-cell parameters: a = 7.082(2) Å, b = 7.796(1) Å, c = 12.05(3) Å, α = 95.37(2)°, β = 98.38(3)°, γ = 62.98(1)°, Z = 2, V = 586.2(1) Å³ and D_x = 1.836 g cm⁻³. The crystal structure has been solved and refined to R = 0.03 using 2328 independent reflections. The structure can be described as infinite (H₂XO)_n chains spreading parallel to the b direction. These chains are themselves interconnected by a set of NH?O hydrogen bonds generated by the organic entities, alternating with the chains. Solid-state ¹³C, ¹⁵N and ³¹P MAS NMR spectroscopies are in agreement with the X-ray structure.     

Synthesis and characterization of 2-amino-3-methylpyridinium dihydrogenomonoarsenate

A new crystal of 2-amino-3-methylpyridinium dihydrogenomonoarsenate has been prepared and characterized by X-ray crystallography, thermal analysis and spectroscopic studies. This compound crystallizes in the triclinic space group with a = 7.2689 (2) Å, b = 8.0975 (2) Å, c = 8.3969 (4) Å, α = 77.09 (3)°, β = 79.20 (3)°, γ = 88.16 (2)°, V = 473.19 (3) Å³, Z = 2. The crystal structure was solved and refined to R = 0.027 with 3375 independent reflections. The atomic arrangement can be described as (H₂AsO₄⁻)_n polymeric chains anchoring the 2-amino-3-methylpyridinium cations through short hydrogen bonds. All the ring atoms of the organic entity are coplanar. The exocyclic N atom is an electron receiving center, which is consistent with features of imino resonance evidenced by bond lengths and angles. Solid-state ¹³C and ¹⁵N CP-MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of carbons and nitrogen to the independent crystallographic sites.     

Crystal growth and structure of R2Ir2O7 (R = Pr, Eu) using molten KF

Single crystals of R₂Ir₂O₇ (R = Pr, Eu) have been synthesized using molten KF at 1373 K. The pyrochlore compounds crystallize in a cubic space group (No. 227, origin choice 2), with Z = 8. At room temperature, the lattice parameters are a = 10.3940(4) Å, V = 1122.92(7) Å³ and a = 10.274(3) Å, V = 1084.5(6) Å³ for Pr₂Ir₂O₇ and Eu₂Ir₂O₇, respectively. In this paper, we report the crystal growth of R₂Ir₂O₇ (R = Pr, Eu) and their structure determinations from single crystal X-ray diffraction experiments at temperatures of 110, 115, and 298 K.     

Determination of the modulated structure of the misfit layer compound (LaS)1.196VS2

Single crystal X-ray diffraction was used to determine the modulated structure of the misfit layer compound (LaS)_1.196VS₂. This compound crystallizes in the triclinic system with cell parameters: a_s = 3.410 (1) Å, b_s = 5.845(1) Å, c_s = 11.191(2) Å, α ≈ 95.15(4), β ≈ 84.79(2)°, and γ ≈ 89.98(2)°, q = 0.5978(4)a_s^* − 0.002(1)b_s^* + 0.004(2)c_s^*, and V_s = 221.2(1) Å³. A (3 + 1)D superspace group, X(α,β,γ), was used to analyze the complete structure (X is referring to a pseudo C centering). The largest modulation amplitudes are observed for La-S (between La (subsystem 2) and S (subsystem 1)), as well as V-V distances. In connection with the large V-V modulation, we observed the formation of “linear vanadium clusters” that may impact on the transport properties.     

Preparation and crystal structure of a new bismuth vanadate, Bi3.33(VO4)2O2

Single crystals of a new bismuth vanadate, Bi_3.33(VO₄)₂O₂ was prepared by hydrothermal reaction using a hydrated sodium bismuthate, NaBiO₃·nH₂O as one of the starting compounds. The crystal structure was determined by using single crystal X-ray diffraction data. This compound crystallizes in the triclinic space group (#2) with a = 7.114(1), b = 7.844(2), c = 9.372(2) Å, α = 106.090(7), β = 94.468(7) and γ = 112.506(8)°, Z = 2 and the final R factors are R1 = 0.052 and wR2 = 0.14 for 2085 unique reflections. The crystal structure is composed by four bismuth atoms with the coordination number of 6 or 8 and two VO₄ tetrahedra, and one of four bismuth atoms is statistically distributed in the splitting sites with the distance of 0.83 Å. This compound exhibited photocatalytic behavior for decomposition of phenol under visible light irradiation and its activity was less than that of monoclinic BiVO₄.     

Synthesis and crystal structure of triphosphate RbPrHP3O10

Crystals of RbPrHP₃O₁₀ have been grown by the flux technique and characterized by single-crystal X-ray diffraction. RbPrHP₃O₁₀ crystallizes in the triclinic space group with lattice parameters: a = 7.0655(5), b = 7.7791(4), c = 8.6828(6) Å, α = 74.074(3), β = 74.270(3), γ = 82.865(2)°, V = 441.09(5) ų, Z = 2. The crystal structure has been solved yielding a final R(F²) = 0.0443 and R_w(F²) = 0.1426 for 1955 independent reflections (F_o² ≥ 2σ(F_o²)). The structure of RbPrHP₃O₁₀ consists of PrO₈ polyhedra and P₃O₁₀⁵⁻ groups sharing oxygen atoms to form a two-dimensional framework; the PrO₈ polyhedra form infinite chains by edge-sharing. Each Rb⁺ ion is bonded to 10 oxygen atoms, these ions are located between chains formed of (HP₃O₁₀)⁴⁻. The energies of the vibrational modes of the crystal were obtained from measurements of the infrared spectrum.     

Crystal growth and structure determinations of potassium hafnates: K2Hf2O5 and K4Hf5O12

Crystals of K₂Hf₂O₅ and K₄Hf₅O₁₂ were grown from molten potassium hydroxide flux. The crystal structures were determined by single-crystal X-ray diffraction. K₂Hf₂O₅ crystallizes in the space group Pnna of the orthorhombic system, with unit cell dimensions of a = 5.780(1) Å, b = 10.640(2) Å, and c = 8.666(2) Å. This compound contains infinite chains of HfO₆ octahedra that form a channel structure. K₄Hf₅O₁₂ crystallizes in the space group of the trigonal system, with unit cell dimensions of a = 5.7877(2) Å and c = 10.3693(7) Å. This compound possesses a layered structure with six-coordinate Hf in three different coordination environments (trigonal prismatic, distorted octahedral, and regular octahedral).     

A new borophosphate chain anion in an organo-templated iron(III) borophosphate: Synthesis, crystal structure and magnetic properties of (C4H12N2)3Fe6(H2O)4[B6P12O50(OH)2]·2H2O

The organo-templated iron(III) borophosphate (C₄H₁₂N₂)₃Fe^III₆(H₂O)₄[B₆P₁₂O₅₀(OH)₂]·2H₂O was prepared under mild hydrothermal conditions (443 K). The crystal structure was determined from single-crystal X-ray data at 295 K (orthorhombic, Pbca (No. 61), Z=4, a=17.8023(7) Å, b=16.1037(5) Å, c=19.1232(6) Å, V=5482.3(3) Å³, R1=0.055, wR2=0.104, 6576 observed reflections with I>2σ(I)) and contains a new type of borophosphate anion: a mixed open- and loop-branched zehner single chain, , built from heptamers [B₂P₅O₂₁] interconnected by BO₃(OH) tetrahedra sharing their third oxygen corners with additional (terminal) PO₄ tetrahedra to form open branchings. The mixed open- and loop-branched single chains running along [0 0 1] are interconnected by three crystallographically independent iron coordination octahedra to form a 3D framework structure containing eight-membered ring channels running along [0 1 0] and cages, which are occupied by two crystallographically independent piperazine cations and H₂O molecules. The displacement parameters of C and N atoms in the piperazine cations are dramatically influenced by the strength of the hydrogen bond reflecting the shape of the cavities. The magnetic investigations indicate the existence of antiferromagnetic interactions as the major components. A narrow hysteresis at low temperatures indicates a weak ferromagnetic component, due to a non-cancellation of spins.     

GexNbSe2 and GexNbS2 intercalation compounds

The structures of two intercalation compounds, Ge_∼0.2NbSe₂ and Ge_∼0.3NbS₂ were investigated by single crystal X-ray diffraction and electron microscopy (selected area electron diffraction (SAED), high resolution electron microscopy (HRTEM) and X-ray microanalysis by energy dispersive spectroscopy (XEDS)). Crystal structure determinations of the average structure of the intercalation compounds 2H-Ge_0.217NbSe₂ and 4H-Ge_0.288NbS₂ are reported: the selenide compound crystallizes in the space group P6₃/mmc with a = 3.4560(9) Å and c = 12.966(3) Å and adopts the 2H-NbSe₂ structure-type, while the sulfide compound crystallizes in the P6₃mc space group, with a = 3.3392(9) Å and c = 25.404(7) Å with a structure-type 4H_c-NbS₂ which it is known for TaSe₂. In both structures the germanium atoms are located in the empty octahedral positions of the van der Waals gap between the NbX₂ (X = S, Se) layers. Electron diffraction patterns from several Ge_xNbSe₂ crystal flakes show different superstructures and exhibit diffracted diffuse intensity: weak satellites corresponding to and 2a₀ × 2a₀ superstructures were observed for x ∼ 0.15 (a₀ is the basal lattice parameter of the host structure). For x ∼ 0.25-0.33, the same type of satellite is observed with a stronger intensity. For x ∼ 0.5 only satellites corresponding to the superstructure were present. In the case of Ge_xNbS₂, with 0.10 < x < 0.25, the germanium atoms are ordered in domains with an superstructure. In some crystals disorder along the c-axis has been observed.     

The crystal structure of eulytite Pb3BiV3O12

The crystal structure of Pb₃BiV₃O₁₂ was solved using single-crystal X-ray diffraction technique. The compound crystallizes in the cubic system (No. 220) with eulytite structure with a = 10.7490(7) Å, V = 1241.95(14) Å³ and Z = 4. The final R₁ value of 0.0198 (wR₂=0.0384) was achieved for 359 independent reflections during the structure refinement. The Pb²⁺ and Bi³⁺ cations occupy the special position (16c) while the oxygen anions occupy the general position (48e) in the crystal structure. Unlike many other eulytite compounds, all the crystallographic positions are fully occupied. The structure consists of edge-shared Pb/Bi octahedra linked at the corners to independent [VO₄]³⁻ tetrahedra units, generating a eulytite-type network in the crystal lattice.     

Crystal structure, thermal analysis and IR spectrometric investigation of bis(o-anisidinium) sulfate (C7H10NO)2SO4

Chemical preparation, X-ray single-crystal, thermal behaviour, and IR spectroscopy investigations are given for a new organic cation sulfate (C₇H₁₀NO)₂SO₄ (denoted BOAS) in the solid state. This compound crystallizes in the monoclinic space group P2₁/c. The unit cell dimensions are: a = 7.010(3) Å, b = 11.142(5) Å, c = 20.770(8) Å, β = 95.27(3)° with V = 1615.4(12) Å³ and Z = 4. The structure has been solved using a direct method and refined to a reliability R factor of 0.047. The title compound consists of a framework of isolated SO₄ tetrahedral interleaved with organic molecules, so as to build isolated ribbons parallel to a-axis. In the present work, we describe the crystal structure, thermal behaviour and IR analysis of this new compound.     

Assessment of the optimum degree of Sr3Fe2MoO9 electron-doping through oxygen removal: An X-ray powder diffraction and Fe Mössbauer spectroscopy study

We describe the preparation and structural characterization by X-ray powder diffraction (XRPD) and Mössbauer spectroscopy of three electron-doped perovskites Sr₃Fe₂MoO_9−δ with Fe/Mo = 2 obtained from Sr₃Fe₂MoO₉. The compounds were synthesized by topotactic reduction with H₂/N₂ (5/95) at 600, 700 and 800 °C. Above 800 °C the Fe/Mo ratio changes from Fe/Mo = 2-1 < Fe/Mo < 2. The structural refinements of the XRPD data for the reduced perovskites were carried out by the Rietveld profile analysis method. The crystal structure of these phases is cubic, space group , with cationic disorder at the two different B sites that can be populated in variable proportions by the Fe atoms. The Mössbauer spectra allowed determining the evolution of the different species formed after the treatments at different temperatures and confirm that Fe ions in the samples reduced at 600, 700 and 800 °C are only in the high-spin Fe³⁺ electronic state.     

Structural characterization, thermal, spectroscopic and magnetic studies of the (C3H12N2)0.75[Mn1.50Fe1.50(AsO4)F6] and (C3H12N2)0.75[Co1.50Fe1.50(AsO4)F6] compounds

The (C₃H₁₂N₂)_0.94[Mn_1.50Fe_1.50^III(AsO₄)F₆] and (C₃H₁₂N₂)_0.75[Co_1.50Fe_1.50^III(AsO₄)F₆] compounds 1 and 2 have been synthesized using mild hydrothermal conditions. These phases are isostructural with (C₃H₁₂N₂)_0.75[Fe_1.5^IIFe_1.5^III(AsO₄)F₆]. The compounds crystallize in the orthorhombic Imam space group. The unit cell parameters calculated by using the patterns matching routine of the FULPROOF program, starting from the cell parameters of the iron(II),(III) phase, are: a = 7.727(1) Å, b = 11.047(1) Å, c = 13.412(1) Å for 1 and a = 7.560(1) Å, b = 11.012(1) Å, c = 13.206(1) Å for 2, being Z = 8 in both compounds. The crystal structure consists of a three-dimensional framework constructed from edge-sharing [M^II(1)₂O₂F₈] (M = Mn, Co) dimeric octahedra linked to [Fe^III(2)O₂F₄] octahedra through the F(1) anions and to the [AsO₄] tetrahedra by the O(1) vertex. This network gives rise two kinds of chains, which are extended in perpendicular directions. Chain 1 is extended along the a-axis and chain 2 runs along the c-axis. These chains are linked by the F(1) and O(1) atoms and establish cavities delimited by eight or six polyhedra along the [1 0 0] and [0 0 1] directions, respectively. The propanediammonium cations are located inside these cavities. The thermal study indicates that the structures collapse with the calcination of the organic dication at 255 and 285 °C for 1 and 2, respectively. The Mössbauer spectra in the paramagnetic state indicate the existence of two crystallographically independent positions for the iron(III) cations and a small proportion of this cation in the positions of the divalent Mn(II) and Co(II) ones. The IR spectrum shows the protonated bands of the H₂N- groups of the propanediamine molecule and the characteristic bands of the [AsO₄]³⁻ arsenate oxoanions. In the diffuse reflectance spectra, it can be observed the bands characteristic of trivalent iron(III) cation and divalent Mn(II) and Co(II) ones in a distorted octahedral symmetry. The calculated Dq and B-Racah parameters for the cobalt(II) phase are 710 and 925 cm⁻¹, respectively. The ESR spectra of compound 1 maintain isotropic with variation in temperature, being g = 1.99. Magnetic measurements for both compounds indicate that the main magnetic interactions are antiferromagnetic in nature. However, at low temperatures small ferromagnetic components are detected, which are probably due to a spin decompensation of the two different metallic cations. The hysteresis loops give values of the remnant magnetization and coercive field of 84.5, 255 emu/mol and 0.01, 0.225 T for phases 1 and 2, respectively.     

Crystal structure and physicochemical properties of a new organic condensed phosphate (C7H10NO)3P3O9·4H2O

Chemical preparation, X-ray characterization, IR spectroscopy and thermal analysis of a new cyclotriphosphate: (C₇H₁₀NO)₃P₃O₉·4H₂O abbreviated as OACTP, are reported. This mixed organo-mineral compound crystallizes in the monoclinic system with P2₁/n space group, the unit cell dimensions are: a = 6.605(3) Å, b = 26.166(3) Å, c = 18.671(8) Å, β = 91.95(3)°, Z = 4 and V = 3255(2) Å³. The structure was solved using a direct method and refined to a reliability R-factor of 0.043 using 3931 independent reflections (I > 2σI). Atomic arrangement exhibits infinite (P₃O₉·2H₂O)_n³ⁿ⁻ chains connected by organic cations. The thermal behavior and the IR spectroscopic studies of this new compound are discussed.     

Synthesis and crystal sructure of a new dihydrogenomonophosphate (4-C2H5C6H4NH3)H2PO4

Chemical preparation, crystal structure, calorimetric, and spectroscopic investigations are given for a new organic-cation dihydrogenomonophosphate, (4-C₂H₅C₆H₄NH₃)H₂PO₄ in the solid state. This compound crystallizes in the orthorhombic space group Pbca with the following unit cell parameters: a=8.286(3) Å, b=9.660(2) Å, c=24.876(4) Å, Z=8, V=1991.2(7) Å³, and D_X=1.442 g cm⁻³. Crystal structure was solved with a final R=0.054 for 3305 independent reflections. The atomic arrangement coaled described as H₂PO₄⁻ layers between which are located the 4-ethylanilinium cations.     

Synthesis and crystal structure of [3,5-(CH3O)2C6H3NH3]4P4O12·4H2O

The chemical preparation and crystal structure are given for a new organic-cation cyclotetraphosphate. This compound is triclinic P-1 with the following unit cell parameters: a=7.857(1) Å, b=8.877(2) Å, c=17.271(3) Å, α=93.94(1)°, β=101.75(2)°, γ=103.72(1)° V=1137.0(4) Å³, Z=1 and ρ_cal=1.467 g cm⁻³. The crystal structure has been determined and refined to R=0.037, using 6291 independent reflections. The atomic arrangement can be described by inorganic layers parallel to the (0 0 1) planes, between which the organic entities are located.