Hydrothermal synthesis and crystal structure of a layered vanadium oxide with an interlayer metal coordination complex: [Co(phen)3][V10O26]·H2O

A novel compound, [Co(phen)₃][V₁₀O₂₆]·H₂O, was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic space group Ccca with a=13.447(3), b=29.936(6), c=23.252(5) Å, V=9360(3) Å³, Z=8 and R=0.0285. Data were collected on a Rigaku R-AXIS RAPID IP diffractometer at 293 K in the range of 1.36<θ<24.99°. The structure of the compound consists of vanadium oxide layers, which are built up from the infinite VO₄ chains by corners and edges sharing. The [Co(phen)₃]²⁺ complexes occupy the interlayer space and contact each other via π−π stacking interactions of the phen groups to form infinite one-dimensional chains.     

Order-disorder at Fe sites in SrFe2/3B″1/3O3 (B″=Mo, W, Te, U) tetragonal double perovskites

We have prepared SrFe_2/3B″_1/3O₃ (B″=Mo, U, Te, and W) double perovskites in polycrystalline form by ceramic methods. Phases with B″=U, Te and W have been studied by X-ray powder diffraction and the results have been compared with neutron diffraction data available for B″=Mo. At room temperature, the stoichiometric samples crystallize in the tetragonal crystal system (space group I4/m, Z=4). Cell parameters when B″=U, Te and W are a=5.6936(1) Å, c=8.0637(1)Å; a=5.5776(1) Å, c=7.9144(3) Å and a=5.5707(3) Å, c=7.9081(5) Å, respectively.The Mössbauer spectra at room temperature for all compounds show hyperfine parameters belonging to two Fe³⁺ sites located at lattice positions with different degrees of distortion. This is in agreement with diffraction data that indicate that the series of compounds display different degrees of Fe-site disorder, which increases in the following sequence: Mo<U<Te<W.     

The Synthesis and Crystal Structure of Doped Uranium Brannerite Phases U1−xMxTi2O6 (M=Ca, La, and Gd)

Doped uranium brannerite phases (U_1−xM_xTi₂O₆; M=Ca²⁺, La³⁺ and Gd³⁺; x<0.5) were synthesized at 1400°C; the range of solid solution was found to vary depending on whether sintering took place in argon or air. Powder X-ray diffraction revealed that these phases crystallized to form monoclinic (C2/m) structures. In particular, the crystal structures of U_0.74Ca_0.26 Ti₂O₆ (1) (a=9.8008(2); b=3.7276(1); c=6.8745(1); β=118.38(1); V=220.97(1); Z=2; R_P=7.3%; R_B=4.6%) and U_0.55La_0.45Ti₂O₆ (2) (a=9.8002(7); b=3.7510(3); c=6.9990(5); β=118.37(4); V=226.40(3); Z=2; R_P=4.5%; R_B=2.9%) were refined from powder neutron diffraction data, revealing planes of corner and edge-sharing TiO₆ octahedra separated by 8-fold coordinate U/M atoms. The oxygen sites within these structures were found to be fully occupied, confirming that the doping of lower valence M atoms occurs in conjunction with the oxidation of U(IV) to U(V).     

The new ternary pnictides Er12Ni30P21 and Er13Ni25As19: Crystal structures and magnetic properties

The new ternary pnictides Er₁₂Ni₃₀P₂₁ and Er₁₃Ni₂₅As₁₉ have been synthesized from the elements. They crystallize with hexagonal structures determined from single-crystal X-ray data for Er₁₂Ni₃₀P₂₁ (space group P6₃/m, a=1.63900(3) nm, c=0.37573(1) nm, Z=1, R_F=0.062 for 1574 F-values and 74 variable parameters), and for Er₁₃Ni₂₅As₁₉ (Tm₁₃Ni₂₅As₁₉-type structure, space group P6?, a=1.6208(1) nm, c=0.38847(2) nm, Z=1, R_F=0.026 for 1549 F-values and 116 variable parameters). These compounds belong to a large family of hexagonal structures with a metal-metalloid ratio of 2:1. HRTEM investigations were conducted to probe for local ordering of the disordered structure at the nanoscale. The magnetic properties of the phosphide Er₁₂Ni₃₀P₂₁ have been studied in the temperature of range 2<T<300 K and with applied fields up to 5 T. The magnetic susceptibility follows the Curie-Weiss law from 4 to 300 K. The measured value of μ_eff=9.59 μ_B corresponds to the theoretical value of Er³⁺.     

Dimorphic cerium(III) oxoarsenate(III) Ce[AsO3]

Colourless, water- and air-stable single crystals of cerium(III) oxoarsenate(III) Ce[AsO₃] were prepared by the reaction of cerium metal (Ce) and arsenic sesquioxide (As₂O₃) in the presence of cesium chloride (CsCl) as fluxing agent at 750 °C in an evacuated silica ampoule. Ce[AsO₃] crystallizes monoclinically (a = 902.89(8), b = 782.54(7), c = 829.68(7) pm, β = 103.393(3)°, Z = 8) in the space group P2₁/c and is isotypic with α-Pb[SeO₃]. There are two crystallographically different Ce³⁺ positions. (Ce1)³⁺ is coordinated by nine oxygen atoms (d(Ce–O) = 244–286 pm) and (Ce2)³⁺ by only eight (d(Ce–O) = 239–273 pm). Both crystallographically different As³⁺ cations form discrete ψ¹ tetrahedra [AsO₃]³⁻ (d(As–O) = 174–179 pm), which are attached to the Ce³⁺ cations via edges and corners. The second monoclinic modification of Ce[AsO₃] with the lattice parameters a = 439.32(4), b = 529.21(5), c = 617.34(6) pm and β = 105.369(3)° with Z = 2 was obtained by high-pressure synthesis (11 GPa, 1200 °C) and has both a higher density (6.31 vs. 6.13 g · cm⁻³) and a higher calculated Madelung part of the lattice energy (15,155 vs. 15,132 kJ · mol⁻¹). It adopts the space group P2₁/m, crystallizing isotypically with La[AsO₃], β-Pb[SeO₃], Pb[SO₃] (scotlandite) or K[ClO₃] and exhibits nine-fold coordinated Ce³⁺ cations exclusively (d(Ce–O) = 254–287 pm) along with tripodal [AsO₃]³⁻ anions (d(As–O) = 175–176 pm). Raman spectroscopy on both phases of Ce[AsO₃] shows stretching vibrations between 769 and 731 cm⁻¹ as well as asymmetric vibrations in the range of 659–617 cm⁻¹. The symmetric bending mode vibrations emerge in an interval from 340 to 410 cm⁻¹ and the asymmetric bending modes range between 230 and 290 cm⁻¹.     

An Unusual Organic-Inorganic Chain-like Hybrid Complex [(CuCl)2(o-phen)]∞ (o-phen=o-phenanthroline)

A novel organic-inorganic hybrid complex [(CuCl)₂(o-phen)]_∞ 1 (o-phen=o-phenanthroline) has been hydrothermally synthesized and structurally characterized by elemental analyses, XPS spectrum, TG analysis, and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P2₁/n, a=3.7285(7) Å, b=19.603(4) Å, c=16.757(3) Å, β=95.83(3)°, V=1218.4(4) ų, Z=4, λ(MoKα)=0.71073 Å (R(F)=0.0643 for 2559 reflections). Data were collected on an R-axis RAPID diffractometer at 293 K in the range of 1.60<θ<27.48°. The title compound exhibits a one-dimensional chain-like scaffolding constructed by the unusual [Cu₃Cl₃] hexagon motifs by sharing opposite edges. Only Cu(1) sites of the [Cu₃Cl₃] hexagon are coordinated with N donors of o-phen groups. Furthermore, the three-dimensional supermolecular architecture is formed by C-H…Cl hydrogen bonds between o-phen groups and CuCl chains.     

Preparation and Crystal Structures of 4-(4′-Pyridylthio)-1-methylpyridinium Salts: Assembly of a Donor-Acceptor-Type Molecule Containing a Sulfide Bridge

A series of ionic 4-(4′-pyridylthio)-1-methylpyridinium salts with different counteranions (1, I⁻; 2, BF⁻₄; 3, PF⁻₆; and 4, OTf⁻, where OTf=trifluoromethanesulfonate) have been prepared. Structural analysis reveals that the cation exhibits a variety of stacking structures dependent on the anion. Compound 1 crystallizes in space group P2_1/n (#14), with a=10.764(3) Å, b=9.601(5) Å, c=13.105(3) Å, β=108.35(2), V=1285.4(8) ų, and Z=4. In this compound, each cation moiety is stacked in a helical arrangement along the c-axis. Compound 2, which is isomorphous to 1, has space group P2_1/n (#14), with a=11.647(2) Å, b=9.203(3) Å, c=13.232(2) Å, β=108.42(2), V=1345.6(5) ų, and Z=4. Compound 3 crystallizes in space group P2_1/n (#14), with a=8.06(1) Å, b=17.43(1) Å, c=10.30(1) Å, β=103.0(1), V=1410(3) ų, and Z=4. In this salt, the cation molecules assume a head-to-tail stacking arrangement, forming a polar pseudo 1-D chain. Compound 4 crystallizes in space group Pb? (#2), with a=7.585(4) Å, b=15.443(7) Å, c=6.775(4) Å, α=99.33(4), β=108.35(2)^o, γ=98.37(4), V=756.6(7) ų, and Z=2. The structure of 4 consists of a columnar stacking of pyridine moieties, with the cation moieties surrounded by the counteranions. Calculations show that the 4-(4′-pyridylthio)-1-methylpyridinium cation may be a good building block for second harmonic generation (SHG) materials, even though salts 1-4 crystallized in centrosymmetric structures and were SHG inactive.     

A novel nitridogallate fluoride LiBa5GaN3F5 – Synthesis,crystal structure,and band gap determination

LiBa₅GaN₃F₅ was obtained as red crystals by reaction of Ba, Ga, NaN₃ and EuF₃ in a Na/Li flux at 760 °C in weld-shut tantalum crucibles. The crystal structure (Pnma (no. 62), a = 15.456(3), b = 5.707(1), c = 12.259(3) Å, Z = 4) was solved on the basis of single-crystal X-ray diffraction data. In the solid there are trigonal planar [GaN₃]^6? ions and zigzag chains of vertex sharing LiF₆ octahedrons surrounded by Ba²⁺ ions. Optical measurements and calculations of the electronic structure revealed a band gap of ≤1.9 eV. According to the calculations, the observed transition occurs from a nitrogen state into a hybrid Ba/N state.     

Anomalous octahedral distortion and multiple phase transitions in the metal-ordered manganite YBaMn2O6

By means of powder X-ray diffraction, powder neutron diffraction and transmission electron microscopy (TEM), we determined the crystal structures of a metal-ordered manganite YBaMn₂O₆ which undergoes successive phase transitions. A high-temperature metallic phase (T_c1=520 K<T) crystallizes in a triclinic P1 with the following unit cell: Z=2, a=5.4948(15) Å, b=5.4920(14) Å, c=7.7174(4) Å, α=89.804(20)°, β=90.173(20)°, γ=91.160(4)°. The MnO₆ octahedral tilting is approximately written as a⁰b⁻c⁻, leading to a significant structural anisotropy within the ab plane. The structure for T_c2<T<T_c1 is a monoclinic P2 (Z=2, a=5.5181(4) Å, b=5.5142(4) Å, c=7.6443(3) Å, β=90.267(4)°) with an a⁻b⁻c⁻ tilting. The structural features suggest a d_x²−y² orbital ordering (OO). Below T_c2=480 K, crystallographically inequivalent two octahedra show distinct volume difference, due to the Mn³⁺/Mn⁴⁺ charge ordering. The TEM study furthermore revealed a unique d_3x²−r²/d_3y²−r² OO with a modified CE structure. It was found that the obtained crystal structures are strongly correlated to the unusual physical properties. In particular, the extremely high temperature at which charge degree of freedom freezes, T_c2, should be caused by the absence of the structural disorder and by heavily distorted MnO₆ octahedra.     

Defects and Luminescence Behavior of Cubic F23 [(NH4(18-Crown-6))4MnX4] [TlX4]2 (X=Cl, Br) Crystals

Luminescence from [(NH₄(18-Crown-6))₄MnBr₄][TlBr₄]₂ (1), [(NH₄(18-Crown-6))₄MnCl₄][TlCl₄]₂ (2), [(NH₄(18-Crown-6))₂MnBr₄] (3), and [(NH₄(18-Crown-6))₂MnCl₄] (4) was studied in search of new insights regarding crystal defects in 2. Emission from 3 and 4 is normal Mn²⁺(⁴T₁(⁴G)→⁶A₁); that of 2 (λ_max≈520 nm at ca. 300 K and 560 nm at 77 K) is unusual and temperature dependent. Thermal barriers (kJ/mol, assignment): green emission of 1 and 2, T<150 K (1-2, NH⁺₄ rotations), 150<T<250 K (7-14, energy migration among [MnX₄]²⁻), 250<T<300 K (26-35, rotations of 18-Crown-6)); yellow emission of 2: T;<250 K (7-8, energy migration among [MnX₄]²⁻), T>250 K (29 kJ/mol, defect-to-Mn²⁺(⁴T₁(⁴G)) back energy transfer). Crystal data for 4: Space group P2₁/c; Z=4; a=20.173(1) Å; b=9.0144(8) Å; c=20.821(1) Å; β=98.782(5)°; V=3741.9(8) ų; R_w=0.059; R=0.054.     

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.     

Structural, spectral and thermal studies of substituted N-(2-pyridyl)-N′-phenylthioureas

N-2-(3-picolyl)-N′-phenylthiourea, 3PicTuPh, monoclinic, P2₁/n, a=7.617(2) b=7.197(5), c=22.889(5) Å, β=94.63(4)°, V=1250.7(1) Å³ and Z=4; N-2-(4-picolyl)-N′-phenylthiourea, 4PicTuPh, triclinic, P-1, a=7.3960(5), b=7.9660(12), c=21.600(3) Å, α=86.401(4), β=84.899(8), γ=77.769(8)°, V=1237.5(3) Å³ and Z=4; N-2-(5-picolyl)-N′-phenylthiourea, 5PicTuPh, monoclinic, P2₁/c, a=14.201(1), b=4.905(3), c=17.689(3) Å, β=91.38(1)°, V=1231.8(7) Å³ and Z=4; N-2-(6-picolyl)-N′-phenylthiourea, 6PicTuPh, monoclinic, C2/c2, a=14.713(1), b=9.367(1), c=18.227(1) Å, β=92.88(1)°, V=2515.5(1) Å³ and Z=8 and N-2-(4,6-lutidyl)-N′-phenylthiourea, 4,6LutTuPh, monoclinic, C2/c, a=11.107(2), b=11.793(2), c=20.084(4) Å, β=96.10(3)°, V=2616(1) Å³ and Z=8. Intramolecular hydrogen bonding between N′H and the pyridyl nitrogen and intermolecular hydrogen bonding involving the thione sulfur are affected by substitution of the pyridine ring, as is the planarity of the molecule. ¹H NMR studies in CDCl₃ show the NH′ hydrogen resonance considerably downfield from other resonances in the spectrum for each thiourea.     

Novel one-dimensional lanthanide acrylic acid complexes: an alternative chain constructed by hydrogen bonding

Novel one-dimensional (1D) chains of three lanthanide complexes La(L¹)₃(CH₃OH)]·CH₃OH (L¹=(E)-3-(2-hydroxyl-phenyl)-acrylic acid) 1, La(L²)₃(H₂O)₂]·2.75H₂O (L²=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) 2, and La(L³)₃(CH₃OH)₂(H₂O)]·CH₃OH (L³=(E)-3-(4-hydroxyl-phenyl)-acrylic acid) 3 are reported. The crystal structure data are as follows for 1: C₂₉H₂₉LaO₁₁, monoclinic, P2₁/n, a=15.4289(12) Å, b=7.9585(6) Å, c=23.041(2) Å, β=99.657(2)°, Z=4, R₁=0.0637, wR₂=0.0919; for 2: C₂₇H_30.50LaO_13.75, triclinic, P−1, a=8.4719(17) Å, b=13.719(3) Å, c=14.570(3) Å, α=62.19(3)°, β=99.657(2)°, γ=78.22(3)°, Z=2, R₁=0.0384, wR₂=0.0820; and for 3: C₃₀H₃₅LaO₁₃, monoclinic, P2(1)/c, a=9.5667(6) Å, b=24.3911(15) Å, c=14.0448(9) Å, β=109.245(2)°, Z=4, R₁=0.0374, wR₂=0.0630. All the three structure data were collected using graphite monochromated molybdenum Kα radiation and refined using full-matrix least-squares techniques on F². These structures show that four kinds of the carboxylato bridge modes are included in these chains to link the La(III) ions. It is the first time that it has been found that the intra-chain hydrogen bonding can construct an alternative chain even, when the coordination bridge mode is the same along the chain (complex 2). There are 2D and 3D hydrogen bonding in the crystal lattices of complexes 1-3.     

Ternary rare-earth zinc arsenides REZn1-xAs2 (RE=La-Nd, Sm)

The ternary rare-earth zinc arsenides REZn_1−xAs₂ (RE=La-Nd, Sm) were prepared by reaction of the elements at 800 °C. Single-crystal and powder X-ray diffraction analysis revealed a defect SrZnBi₂-type average structure for the La member (Pearson symbol tI16, space group I4/mmm, Z=4; a=4.0770(9) Å, c=20.533(5) Å), in contrast to defect HfCuSi₂-type average structures for the remaining RE members (Pearson symbol tP8, space group P4/nmm, Z=2; a=4.0298(5)-3.9520(4) Å, c=10.222(1)-10.099(1) Å in the progression from Ce to Sm). The homogeneity range is not appreciable (estimated to be narrower than 0.6<1−x<0.7 in SmZn_1−xAs₂) and the formula REZn_0.67As₂ likely represents the Zn-rich phase boundary. The Ce-Nd members are Curie-Weiss paramagnets. LaZn_0.67As₂ shows activated behavior in its electrical resistivity, whereas SmZn_0.67As₂ exhibits anomalies in its temperature dependence of the electrical resistivity.     

Pentiptycene‐Derived Light‐Driven Molecular Brakes: Substituent Effects of the Brake Component

Five pentiptycene‐derived stilbene systems ( 1 R ; R =H, OM, NO, Pr, and Bu) have been prepared and investigated as light‐driven molecular brakes that have different‐sized brake components ( 1 H < 1 OM < 1 NO < 1 Pr < 1 Bu ). At room temperature (298 K), rotation of the pentiptycene rotor is fast (k_rot=10⁸–10⁹ s^?1) with little interaction with the brake component in the trans form ((E)‐ 1 R ), which corresponds to the brake‐off state. When the brake is turned on by photoisomerization to the cis form ((Z)‐ 1 R ), the pentiptycene rotation can be arrested on the NMR spectroscopic timescale at temperatures that depend on the brake component. In the cases of (Z)‐ 1 NO , (Z)‐ 1 Pr , and (Z)‐ 1 Bu , the rotation is nearly blocked (k_rot=2–6 s^?1) at 298 K. It is also demonstrated that the rotation is slower in [D₆]DMSO than in CD₂Cl₂. A linear relationship between the free energies of the rotational barrier and the steric parameter A values is present only for (Z)‐ 1 H , (Z)‐ 1 OM , and (Z)‐ 1 NO , and it levels off on going from (Z)‐ 1 NO to (Z)‐ 1 Pr and (Z)‐ 1 Bu . DFT calculations provide insights into the substituent effects in the rotational ground and transition states. The molar reversibility of the E–Z photoswitching is up to 46 %, and both the E and Z isomers are stable under the irradiation conditions.     

Divalent transition metal phosphonates with new structure containing hydrogen-bonded layers of phosphonate anions

A series of divalent transition metal phosphonates containing hydrogen-bonded layers of phosphonate anions, namely [M(phen)₃]·C₆H₅PO₃·11H₂O [M=Co(1), Ni(2), Cu(3)] and [Cd(phen)₃]·C₆H₅PO₃H·Cl·7H₂O (4) have been synthesized, structurally characterized by single-crystal X-ray diffraction method. These compounds all crystallize in the triclinic system, space group P-1. The lattice parameters are a=12.1646(5), b=12.4155(6), c=15.4117(10) Å, α=78.216(2), β=79.735(3), γ=77.8380(3)°, V=2205.1(2) Å³, Z=2 for 1; a=12.097(2), b=12.606(3), c=15.742(3) Å, α=76.66(3), β=80.04(3), γ=77.75(3)°, V=2263.4(8) Å³, Z=2 for 2; a=12.058(2), b=12.518(3), c=15.781(3) Å, α=77.77(3), β=80.02(3), γ=77.91(3)°, V=2255.5(8) Å³, Z=2 for 3 and a=12.47680(10), b=12.6693(2), c=16.1504(3) Å, α=82.600(1), β=71.122(1), γ=77.355(1)°, V=2352.37(6) Å³, Z=2 for 4. All structures are refined by full-matrix least-squares methods [for 1, R1=0.0602 using 6458 independent reflections with I>2σ(I); for 2, R1=0.0632 using 4657 independent reflections with I>2σ(I); for 3, R1=0.0634 using 6221 independent reflections with I>2σ(I); for 4, R1=0.0400 using 7930 independent reflections with I>2σ(I)]. In the crystal structures, the phenylphosphonate anions and water molecules are hydrogen-bonded to form layers, and there exist the cationic species [M(phen)₃]²⁺ between the adjacent layers of anions and water. Luminescence, thermal analysis as well as IR spectroscopic studies are also presented.     

Crystal structure and phonon properties of noncentrosymmetric LiNaB4O7

A new borate, LiNaB₄O₇, has been synthesized and characterized by single-crystal X-ray structure determination. The material crystallizes in the orthorhombic system, noncentrosymmetric space group Fdd2, with unit cell dimensions a=13.325(2), b=14.099(2), c=10.243(2) Å, Z=16, and V=1924.3(7) Å³. Like Li₂B₄O₇, the structure is built of two symmetrically independent, interpenetrating polyanionic frameworks built from condensation of the B₄O₉ fundamental building block, which is comprised of two distorted BO₄ tetrahedra and two BO₃ triangles. The interpenetrating frameworks produce distinct tunnels that are selectively occupied by the Li and Na atoms. Large single crystals exhibiting an optical absorption edge with λ<180 nm have been grown via the top-seeded-solution-growth method. The SHG signal (0.15× potassium dihydrogen phosphate (KDP)) is consistent with the calculated components of the SHG tensor and the approximate centrosymmetric disposition of the independent and interpenetrating frameworks. A complete analysis of polarized IR and Raman spectra confirms a close relationship between the title compound and Li₂B₄O₇.