Eightfold Coordination Research Articles

Crystal structures of coordination polymers from CaI2 and proline.

Completing our reports concerning the reaction products from calcium halides and the amino acid proline, two different solids were found for the reaction of l- and dl-proline with CaI2. The enanti-opure amino acid yields the one-dimensional coordination polymer catena-poly[[aqua-μ3-l-proline-tetra-μ2-l-proline-dicalcium] tetra-iodide 1.7-hydrate], {[Ca2(C5H9NO2)5(H2O)]I4·1.7H2O} n , (1), with two independent Ca(2+) cations in characteristic seven- and eightfold coordination. Five symmetry-independent zwitterionic l-proline mol-ecules bridge the metal sites into a cationic polymer. Racemic proline forms with Ca(2+) cations heterochiral chains of the one-dimensional polymer catena-poly[[di-aquadi-μ2-dl-proline-calcium] diiodide], {[Ca(C5H9NO2)2(H2O)2]I2} n , (2). The centrosymmetric structure is built by one Ca(2+) cation that is bridged towards its symmetry equivalents by two zwitterionic proline mol-ecules. In both structures, the iodide ions remain non-coordinating and hydrogen bonds are formed between these counter-anions, the amino groups, coordinating and co-crystallized water mol-ecules. While the overall composition of (1) and (2) is in line with other structures from calcium halides and amino acids, the diversity of the carboxyl-ate coordination geometry is quite surprising.

The crystal structure of the compound Pb6Cu+(AsO3)2Cl7 discovered in the ancient slags of Lavrion, Greece

Abstract Lead and copper(I) chloride arsenite was found in the ancient metallurgic slag from the Vrissaki area, Lavrion district, Attikí Peninsula, Greece. Its chemical composition corresponds to the idealized formula Pb6Cu+(AsO3)2Cl7. The IR spectrum shows the presence of A s O 3 3 − $AsO_3^{3 - }$ anions and only a trace amount of O–H bonds. The crystal structure was solved by direct methods and refined to R(F) = 0.0304 based on 1778 unique reflections with I > 2σ(I). The compound is trigonal (rhombohedral), R3̅, a = 9.8691(2), c = 34.2028(13) Å, V = 2885.01(14) Å3, Z = 6. Two crystallographically non-equivalent As3+ cations occupy apexes of the AsO3 pyramids. Cu+ cation occupies an apex of the CuCl3 pyramid. The group [Cl3Cu–AsO3] is arranged along the c axis. Pb cations occupy two sites with seven- and eight-fold coordination. The crystal-chemical formula of the compound is Pb6(Cu+Cl3)(As3+O3)2Cl4.

Lithium and sodium diffusion in solid electrolyte materials of AM2(PO4)3(A = Li, Na, M = Ti, Sn and Zr)

Electrolytes with a high ionic conductivity are the prerequisite for the success of solid state rechargeable ion batteries. In this paper, density functional theory (DFT) calculations are applied in combination with a climbing-image nudged elastic band (CI-NEB) method to obtain the diffusion barriers of the lithium (Li) and sodium (Na) in stoichiometric AM 2( PO 4)3 (A = Li, Na, M = Ti, Sn and Zr) compounds. In the AM 2( PO 4)3, Li and Na ions occupy the interstitial sites, M1, which is coordinated by a trigonal antiprism of oxygen, and M2, which has a distorted eight-fold coordination. Results show that the diffusion barriers are closely related with the average bond length of A–O bond when the atom A occupies the M2 site in the AM 2( PO 4)3 compounds, and the diffusion barriers decrease with increasing the average bond length. Among the various types of the AM 2( PO 4)3 compounds, the AM 2( PO 4)3 has a good potential for solid electrolytes due to its low diffusion barriers for the Li and Na.

Synthesis and photoluminescence properties of fluorite-related (Y1−xEux)10W2O21 phosphor

Eu3+-doped fluorite-related yttrium–tungsten oxide Y10W2O21 (5Y2O3·2WO3) was prepared using vibrating-mill-mixed powder and solid-state reactions. The synthesis temperature was investigated by thermogravimetric/differential thermal analysis and X-ray diffraction. The morphology of the phosphor was confirmed by scanning electron microscope (SEM) measurement. The photoluminescence (PL) properties, including the excitation and emission spectra, decay curves (lifetime), thermal stability and quantum efficiency, were investigated. The PL emission intensity was found to increase with Eu3+ content up to about 22.5mol% and then decrease due to the concentration quenching effect. There were two kinds of coordinating site (seven-fold coordination and eight-fold coordination) of Y3+ ions in the fluorite-related structure of Y10W2O21. Eu3+ in different coordinating sites of Y3+ in the host could lead to energy-level splitting of the 5D0→7F2 transition, resulting in an emission peak red shift. The major intensity emission wavelengths, located at 612nm and 627nm for excitation at 392nm, were attributed to replacement of the Eu3+ ions with 7 or 8 coordination sites of Y3+ ions.

Crystal Structures of Pigment Red 57:1

Zeitschrift für Kristallographie, Angewandte Chemie, The New York Times, The Sun, El Pais, La Republica, Le Monde, Shanghai Daily, and many more journals and newspapers are printed with Pigment Red 57:1. P.R.57:1 (C18H12CaN2O6S · n H2O, n = 0,1,3) is the most important organic red pigment with a production of more than 50,000 tons per year and an annual sales volume of more than 200 million Euro.[1] In printing ink the pigment is not dissolved, but finely dispersed. Consequently its solid-state properties are maintained. Like most pigments, P.R.57:1 occurs in different crystal phases with different colours. Upon synthesis a trihydrate is formed. Drying at 500C generates a monohydrate with magenta shade, which is used for printing inks. The monohydrate is thermally stable up to temperatures higher than 1900C before it releases water to yield a hygroscopic anhydrous phase with dull dark magenta shade. For all three phases the growth of single crystals is impeded by the low solubility of the pigment in most media. The crystal structures of all three forms were determined from in-house X-ray powder data.[2] The structures were solved by real-space methods with simulated annealing. Subsequently a Rietveld refinement with restraints on bond lengths, bond angles and planar groups was performed. All three phases crystallize in space-group type P21/c, Z = 4. The trihydrate and the monohydrate show eightfold coordination of the Ca ions, the anhydrate a sevenfold one. Apparently the increasing anion-cation interactions lead to the observed colour shift. The arrangement of cations and anions is similar in all three forms. The crystal structures exhibit double layers, one polar, one nonpolar. The polar layer consists of water molecules, calcium ions, sulfonate, keto and carboxylate groups, held together mostly by hydrogen bonds and Coulomb interactions. The nonpolar layer contains naphthalene and toluene moieties.

Relationships between structural and electrical properties in mixed conductors duplex materials in the ZrO2-Y2O3-TiO2ternary system

Duplex materials constituted by 0.50 mol titania-doped yttria-stabilized zirconia (YSZ) and 0.50 mol titania-doped yttria-tetragonal zirconia polycrystalline (YTZP) solid solutions in the ZrO${}_{2}$-Y${}_{2}$O${}_{3}$-TiO${}_{2}$ ternary system can be obtained using different processing strategies. In this study, different amounts of TiO${}_{2}$ dopant and different sintering times have been used for the preparation of the duplex materials: Doping YSZ with 10 mol% of TiO${}_{2}$ and sintering in air for 8 h (10Ti8h) and doping YSZ with 15 mol% of TiO${}_{2}$ and sintering in air for 2 h (15Ti2h) are both successful routes to obtain duplex materials. If we compare the field emission scanning electron microscopy-energy dispersive x-ray analyses of each cubic and each tetragonal solid solution of the two duplex materials, we conclude that the composition of each phase is different from each other, as was expected. The total ionic conductivity of both duplex samples is strongly reduced with respect to that of YSZ, and this reduction increases with the Ti content. In addition, the activation energy for ionic migration in 10Ti8h and 15Ti2h is lower than that for YSZ but higher than that for YTZP, as expected in terms of the relative amount of both YSZ and YTZP fractions in the materials. X-ray absorption spectroscopy (XAS) results, both x-ray absorption near-edge structure and extended x-ray absorption fine structure, show that Ti is sixfold coordinated in both the cubic and tetragonal phases of the duplex materials, departing from the eightfold coordination expected if a simple substitution at the Zr sites would take place. The XAS results also point out that the ability of Ti to trap oxygen vacancies in the cubic phase increases as Ti content does, in agreement with the electrical conductivity behavior, which cannot be accounted for in terms of a dilution effect.

Na2Y3Cl3[TeO3]4: Synthesis, Crystal Structure and Spectroscopic Properties of the Bulk Material and its Luminescent Eu3+-doped Samples

Colorless, platelet-shaped single crystals of Na2Y3Cl3[TeO3]4 were synthesized by a reaction of Y2O3 and TeO2 (molar ratio 3 : 8) in evacuated silica ampoules within five days at 775 °C with an excess of NaCl added as flux and reagent. The new quintenary compound crystallizes in the monoclinic space group C2/c with the lattice parameters a = 2380:69(14), b = 552:76(3), c = 1662:48(9) pm, β = 134:045(3)° and Z = 4. The crystal structure presents one of the rare oxotellurates(IV) containing isolated [TeO3]2− units, which could be verified by Raman spectroscopy. Doping with Eu3+ (3 mass-%) at the Y3+ sites in eightfold oxygen coordination leads to a strong orange-red luminescence of Na2Y3Cl3[TeO3]4:Eu3+ under UV excitation with a wavelength of λ = 254 nm. Beyond the electronic Eu3+ transitions of the 4 f 6 state, the fluorescence excitation spectrum shows an intense broad charge-transfer band resulting from both O2−→Eu3+ ligand-to-metal charge-transfer (LMCT) as well as electronic Eu3+ d→f and Te4+s→p transitions. The emission spectrum features the prominent f→f transitions of Eu3+-doped oxidic compounds. The optical band gaps of the undoped and doped samples were determined by diffuse reflectance spectroscopy revealing just minimal doping effects on the crystal structure. The optical band gaps could be assigned in the excitation spectrum in the charge-transfer broad-band region supporting the assumption of an inorganic antenna effect of the Te4+ cations.

Accommodation of niobium and cerium variable valence cations in the crystal lattice of the Ln 2 3+ Ti 2 4+ O7 (Ln = Dy, Yb) pyrochlores

We have studied the accommodation of niobium and cerium variable valence cations in the Ln 2 3+ Ti 2 4+ O7 (3+/4+) (Ln = Dy, Yb) pyrochlores in air and in a 5% H2 + 95% Ar reducing atmosphere. The (Dy0.8Ca0.1Ce0.1)2Ti2O7 − δ and (Yb0.8Tb0.1Ca0.1)2[Ti1−x Nb x ]2O7 − δ (x = 0–0.3) oxygen ion conducting solid solutions were synthesized through coprecipitation followed by heat treatment in air for 4 h at temperatures of 1400 and 1550°C, respectively. According to X-ray photoelectron spectroscopy (XPS) data, the valence state of the niobium in the (Yb0.8Tb0.1Ca0.1)2[Ti1−x Nb x ]2O7 − δ (x = 0.05, 0.1) solid solutions is 4+ and, hence, isovalent niobium substitution for titanium takes place. During synthesis in air, the titanium sublattice of the (Yb0.8Tb0.1Ca0.1)2[Ti1−x Nb x ]2O7 − δ pyrochlores is stable when the Nb4+ content does not exceed 10% (x = 0.1). According to conductivity data for the high-conductivity material (Yb0.8Tb0.1Ca0.1)2[Ti0.95Nb0.05]2O6.9 at low oxygen partial pressures, there is no reduction of pentavalent niobium and no increase in electronic conductivity, which is supported by XPS results that only Nb4+ is present in the solid solution. In pyrochlore-like (Dy0.8Ca0.1Ce0.1)2Ti2O7 − δ synthesized in air at 1400°C, the dysprosium site contains both tri- and tetravalent cerium, as supported by conductivity measurements under reducing conditions. The Ce4+ + e → Ce3+ reduction process led to a change in the color and disintegration of the sample when the oxygen partial pressure was reduced. In the 3+/4+ A2B2O7 pyrochlores, variable valence cations on the A site (eightfold coordination) more readily participate in redox processes than do those on the B site (sixfold coordination).

Lusernaite-(Y), Y4Al(CO3)2(OH,F)11{middle dot}6H2O, a new mineral species from Luserna Valley, Piedmont, Italy: Description and crystal structure

The new mineral species lusernaite-(Y), ideally Y4Al(CO3)2(OH,F)11·6H2O, has been discovered in small fractures of the “Luserna Stone,” a leucocratic orthogneiss belonging to the Dora-Maira massif, Western Alps, Italy. It occurs as colorless, thin platelets, with white streak and mica-like pearly luster, elongated along [100] and flattened on {010}, arranged in radiating aggregates. Lusernaite-(Y) is associated with aeschynite-(Y), albite, “chlorite,” hematite, pyrite, quartz, and titanite. Lusernaite-(Y) has a perfect cleavage on {010} and a less marked one probably on {100}. Its calculated density is 2.810 g/cm3. In plane-polarized light, it is transparent, with parallel extinction and positive elongation. Lusernaite-(Y) is biaxial positive; its optical orientation is a = Z , b = X , c = Y . Owing to the crystal morphology, only two refractive indices could be measured, corresponding to β = 1.566(2) and γ = 1.577(2). Lusernaite-(Y) is orthorhombic, space group Pmna , with a = 7.8412(3), b = 11.0313(5), c = 11.3870(4) A, V = 984.96(7) A3, Z = 2. Main diffraction lines of the X-ray powder diffraction pattern are [ d in A, ( I ), ( hkl )]: 11.02 (100) (010), 7.90 (49) (011), 5.66 (25) (002), 5.06 (24) (012), 4.258 (33) (112), 3.195 (27) (220), 3.095 (21) (212). Raman spectroscopy confirmed the presence of CO3 groups (sharp peak at 1096 cm−1); due to the very strong luminescence, the bands of the OH and H2O groups could not be seen. Chemical analyses by electron microprobe gave (wt%) Al2O3 6.11, Y2O3 43.52, La2O3 0.02, Ce2O3 0.04, Nd2O3 0.03, Sm2O3 0.16, Gd2O3 1.39, Dy2O3 3.46, Er2O3 3.15, Yb2O3 2.09, CaO 0.33, PbO 0.37, H2O 22.76, CO2 9.95, F 1.40, O≡F −0.59, sum 94.19; H2O and CO2 were determined from structure refinement. The empirical formula by assuming the presence of 2 (CO3)2− groups, 11 (OH,F)− anions, and 6 H2O groups, in agreement with micro-Raman and structural results, is (Y3.41Dy0.16Er0.15 Yb0.09Gd0.07Ca0.05Pb0.02Sm0.01)∑3.96Al1.06(CO3)2.00(OH10.35F0.65)∑11.00·6H2O. The crystal structure was solved by direct methods and refined on the basis of 840 observed reflections to R 1 = 6.8%. In the structure of lusernaite-(Y), yttrium and REE cations occupy two distinct sites, Y1 and Y2, both in eightfold coordination. The structure is built by layers parallel to (010), formed by chains of edge-sharing Y-centered polyhedra (Y1), which run along [100], and are connected along c through Al-centered octahedra. These chains are decorated on one side by corner-sharing chains of Y-centered polyhedra (Y2), and on the other side by CO3 groups. Along [001] the decorated chains alternate their polarity. Lusernaite-(Y), named after the type locality, the Luserna Valley, shows a new kind of structure among the natural carbonates of REE. Its origin is related to the circulation of hydrothermal solutions during the late-stage Alpine tectono-metamorphic events.

Importance of Counteranions on the Hydration Structure of the Curium Ion

Using density functional theory based ab initio molecular dynamics and metadynamics, we show that counterions can trigger noticeable changes in the hydration shell structure of the curium ion. On the basis of the free energies of curium–water coordination, the eight-fold coordination state is dominant by at least 98% in the absence of counteranions and in the presence of chloride and bromide counteranions. In addition, the solvent hydrogen bond (HB) lifetimes are relatively longer. In contrast, the solvent hydrogen bond (HB) lifetimes are relatively shorter in the presence of perchlorate counteranions, with the nine-fold and eight-fold states existing in an 8/2 ratio, which is in good agreement with the reported ratio measured by X-ray scattering experiments. To our knowledge, this is the first time that molecular simulations have shown that counteranions can directly affect the first hydration shell structure of a cation.

Heterometallic Clusters [CuSn3S9]5− and [Cu6Sn6S20]10−: Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f-3d thiostannates with general formula [Hen]₂[Ln(en)₄(CuSn₃S₉)]∙0.5 en (Ln1; Ln=La, 1; Ce, 2) and [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀]∙3 en (Ln2; Ln=Nd, 3; Gd, 4; Er, 5) were prepared by reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn₂S₆]⁴⁻) compounds and CuS powder. In 1 and 2, three SnS₄ tetrahedra and one CuS₃ triangle are joined by sharing sulfur atoms to form a novel [CuSn₃S₉]⁵⁻ cluster that coordinates to the Ln(3+) ion of [Ln(en)₄]³⁺ (Ln=La, Ce) as a monodentate ligand. The [CuSn₃S₉]⁵⁻ unit is the first thio-based heterometallic adamantane-like cluster coordinating to a lanthanide center. In 3-5, six SnS₄ tetrahedra and six CuS₃ triangles are connected by sharing common sulfur atoms to form the ternary [Cu₆Sn₆S₂₀ ]¹⁰⁻ cluster, in which a Cu₆ core is enclosed by two Sn₃S₁₀ fragments. The topological structure of the novel Cu₆ core can be regarded as two Cu₄ tetrahedra joined by a common edge. The Ln³⁺ ions in Ln1 and Ln2 are in nine- and eightfold coordination, respectively, which leads to the formation of the [CuSn₃S9]⁵⁻ and [Cu₆Sn₆S₂₀]¹⁰⁻ clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1-5 exhibit bandgaps in the range of 2.09-2.48 eV depending on the two different types of clusters in the compounds. Compounds 1, 3, and 4 lost their organic components in the temperature range of 110-350 °C by multistep processes.

Structural study of SrPrZnRuO6, SrPrCoRuO6, SrPrMgRuO6 and SrPrNiRuO6 double perovskite oxides by symmetry-adapted mode analysis

Powder SrPrZnRuO6, SrPrCoRuO6, SrPrMgRuO6 and SrPrNiRuO6 double perovskites were synthesized by the solid-state reaction method, and their crystal structure was investigated by Rietveld analysis (using the symmetry-mode procedure) by x-ray, synchrotron and neutron powder diffraction data. SrPrMRuO6 materials are monoclinic perovskites at room temperature, adopting the space group P21/n, , c ≈ 2ap, Z = 2. The unit cell parameters increase through the series as the B-cation size increases. The tilting of the octahedra is associated with irreducible representations GM+4 and X+3. In the studied series, Sr2+/Pr3+ are in eight-fold coordination and are displaced from the center of the Sr/PrO8 polyhedron along [010] by the X+5(A10) mode. The size of the first coordination sphere of Sr/Pr increases and the second coordination sphere reduces with temperature, suggesting an actual change in coordination. While changing the interatomic distances, the distortion of the structure diminishes, as observed in distortion mode amplitudes and octahedral tilt angles. The temperature driven phase transition was observed for Ni and Mg materials at ≈1025 K and 950 K, respectively. Tilting of the octahedra in the trigonal phase is associated with GM+4, which is the unique active mode associated with the not experimentally observed phase transition.

High-pressure phase transitions of Fe3-xTixO4 solid solution up to 60 GPa correlated with electronic spin transition

The structural phase transition of the titanomagnetite (Fe 3-x Ti x O 4 ) solid solution under pressures up to 60 GPa has been clarified by single-crystal and powder diffraction studies using synchrotron radiation and a diamond-anvil cell. Present Rietveld structure refinements of the solid solution prove that the prefered cation distribution is based on the crystal field preference rather than the magnetic spin ordering in the solid solution. The Ti-rich phases in 0.734 ≤ x ≤1.0 undergo a phase transformation from the cubic spinel of F̅d̅3̅m to the tetragonal spinel structure of I4 1 /amd with c/a < 1.0. The transition is driven by a Jahn-Teller effect of IV Fe 2+ (3d 6 ) on the tetrahedral site. The c/a < 1 ratio is induced by lifting of the degeneracy of the e orbitals by raising the d x2-y2 orbital below the energy of the dz 2 orbital. The distortion characterized by c/a < 1 is more pronounced with increasing Ti content in the Fe 3-x Ti x O 4 solid solutions and with increasing pressure. An X-ray emission experiment of Fe 2 TiO 4 at high pressures confirms the spin transition of FeKβ from high spin to intermediate spin (IS) state. The high spin (HS)-to-low spin (LS) transition starts at 14 GPa and the IS state gradually increases with compression. The VI Fe 2+ in the octahedral site is more prone for the HS-to-LS transition, compared with Fe 2+ in the fourfold- or eightfold-coordinated site. The transition to the orthorhombic post-spinel structure with space group Cmcm has been confirmed in the whole compositional range of Fe 3-x Ti x O 4 . The transition pressure decreases from 25 GPa (x = 0.0) to 15 GPa (x = 1.0) with increasing Ti content. There are two cation sites in the orthorhombic phase: M1 and M2 sites of eightfold and sixfold coordination, respectively. Fe2+ and Ti4+ are disordered on the M2 site. This structural change is accelerated at higher pressures due to the spin transition of Fe 2+ in the octahedral site. This is because the ionic radius of VI Fe 2+ becomes 20% shortened by the spin transition. At 53 GPa, the structure transforms to another high-pressure polymorph with Pmma symmetry with the ordered structure of Ti and Fe atoms in the octahedral site. This structure change results from the order-disorder transition.

First-principles calculations of equilibrium Mg isotope fractionations between garnet, clinopyroxene, orthopyroxene, and olivine: Implications for Mg isotope thermometry

Equilibrium fractionation factors of Mg isotopes at high temperature and pressure are investigated for pyrope, majorite, clinopyroxene, orthopyroxene, and olivine using density functional theory. The calculated equilibrium fractionation factors are in good agreement with previous study (Schauble, 2011), suggesting that our calculations are reliable and accurate. The results reveal significant inter-mineral Mg isotope fractionations due to different coordination environment of Mg in minerals. Specifically, pyrope, where Mg is in eight-fold coordination, is more enriched in light Mg isotopes than olivine and pyroxene where Mg is in six-fold coordination. The calculated isotope fractionation for Mg isotopes between clinopyroxene and pyrope is consistent with observations from natural eclogites (Li et al., 2011; Wang et al., 2012). Our calculation also reveals substantial pressure effect on Mg isotope fractionations among garnet, pyroxene, and olivine.Equilibrium fractionation of Mg isotopes between pyrope and pyroxene (and olivine) could be used as a novel and independent thermometry with precision much better than the traditional garnet–clinopyroxene Fe–Mg exchange thermometry because such fractionation is significantly greater than the current uncertainties of Mg isotope analyses (∼0.05‰amu−1). These Mg isotope thermometries could have wide applications in high-temperature mafic igneous and metamorphic rocks where garnet co-exists with pyroxene or olivine. Equations for equilibrium Mg isotope fractionation factors between garnet (pyrope and majorite) and pyroxene and between garnet and olivine as a function of temperature and pressure are also presented in this study.

(H2en)0.5[BiO(OH)2(H2O)]: The first organic templated layered bismuthate

A novel 2-D organic templated bismuth–oxygen compound (H 2 en) 0.5 [BiO(OH) 2 (H 2 O)] ( 1 ) (en = ethylenediamine) has been synthesized in the presence of ethylenediamine acting as a template under mild hydrothermal conditions. The structure was determined by single crystal X-ray diffraction and further characterized by IR spectrum, elemental analysis, scanning electron microscopy (SEM), photoluminescence and thermogravimetric analysis. In the compound, the Bi atom was coordinated by eight oxygen atoms. The BiO 8 polyhedra share edges or corners with their neighbors to result in an anionic inorganic layer with protonated ethylenediamine cations occupied between layers. At ambient temperature, 1 shows a blue emission band which may be assigned to the 1 P 1 – 1 S 0 transitions of the s 2 electron of the Bi 3 + ion. To our knowledge, 1 is the first example of layered bismuthate templated by an organic amine. A new 2-D organic templated bismuth–oxygen compound (H 2 en) 0.5 [BiO(OH) 2 (H 2 O)] is firstly reported. The BiO 8 polyhedra share edges or corners with the neighboring BiO 8 polyhedra resulting in a layer and the protonated ethylenediamine molecules occupied between layers. ► The first organic template bismuthate compound is reported. ► The Bi atom has eight-fold coordination. ► The compound displays photoluminescence property.

AgCe(PO3)4: Synthesis, crystalline structure and ionic conductivity

Single crystals of a new phosphate AgCe(PO3)4 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P21/c and its parameters are: a=7.314(1)Å, b=13.239(1)Å, c=12.401(1)Å, β=125.69(1)°, V=975.29(2)Å3 and Z=4. The crystal structure was solved from 3160 X-ray independent reflections with final R(F2)=0.037 and Rw(F2)=0.105 refined with 164 parameters (F02 >4σ(F02). The structure of AgCe(PO3)4 consists of CeO8 polyhedra sharing oxygen atoms with phosphoric group PO4 to form a three-dimensional framework. This type of organization gives rise to a three-dimensional framework. Cerium atoms have an eight-fold coordination while silver atoms have approximately six oxygen neighbours.The conductivity as well as the vibrational study of the cerium phosphate were analyzed in order to explain the mechanism of conduction. Activation energies of 0.57eV, deduced from the Arrhenius relation.

Macrocycles based on magnetically functionalized zirconium oxide clusters

In the presence of 4,4′-bipyridine and Co(II) or Ni(II) groups, which are coordinatively constrained by bis-alkoxyamine chelating groups, dimeric [Zr6IVO4(OH)4(RCOO)12]2 clusters rearrange to {Zr12O11(OH)11(RCOO)16} frameworks featuring highly condensed zirconium oxide cores. These {Zr12} groups subsequently each coordinate to three M(II) groups and self-assemble via two bridging 4,4′-bpy into 2.6nm {M6Zr24}-type macrocycles of composition [M6Zr24O22(OH)22(C2H5COO)40(Hmdea)2(H2mdea)4(4,4′-bpy)2]. Surprisingly, two M(II) sites peripherally attached to the {Zr12} frameworks adopt a rare eightfold coordination mode where the M2+ ions reside in a distorted square antiprismatic O7N environment. Magnetic measurements reveal that the zirconium oxide fragments efficiently mediate antiferromagnetic exchange between Ni2+ spin centers, whereas in case of the virtually isostructural Co2+ derivative pronounced ligand field asymmetry causes single-ion effects to significantly influence the low-field susceptibility data.

Self-assembly of 1D coordination polymers of two rare-earth complexes with carboxylate linkages: Synthesis, crystal structure and DFT studies

Two new lanthanide carboxylato complexes [Ln(3,5-DNBA) 3(H 2O) 2] n , (Ln = La III in 1 and Gd III in 2, DNBA = dinitrobenzoic acid) have been synthesized hydrothermally and characterized structurally by single crystal X-ray analysis. Alternate (μ-η 1:η 1) 4 and (μ-η 1:η 1) 2 type bridging modes by carboxylate ligands provide eightfold coordination around the Ln center in both complexes, which result in two different Ln ⋯ Ln distances, with polymeric chains propagating along the [1 0 0] direction. Intermolecular O–H ⋯ O hydrogen bonds and π–π stacking interactions form R 2 2 (20), R 4 4 (40) rings, thus generating three-dimensional supramolecular frameworks in 1 and 2. Density functional theory (DFT) calculations were carried out using the hybrid exchange–correlation functional, PBE. The HOMO–LUMO energy gap of 2.63 eV in 1 is found to be greater than that of 1.86 eV in 2.

On Ammonium‐tetrakis(dithiocarbamato)‐bismuth(III)‐monohydrate and Tris(dithiocarbamato)‐bismuth(III)

AbstractThe title compounds were prepared from aqueous alcoholic solutions by reaction of ammoniumdithiocarbamate with bismuth trichloride. NH4Bi(S2CNH2)4·H2O crystallises in the monoclinic space group P21/c (No. 14) with a = 8.4109(17), b = 13.198(3) and c = 16.678(3) Å, β = 97.17(3)°and Bi(S2CNH2)3 crystallises in the triclinic space group P$\bar{1}$ (No. 2) with a = 5.8951(5), b = 8.3026(7), c = 12.5030(10) Å, α = 103.460(10), β = 95.080(10) and γ = 91.330(10) °. The crystal structure of NH4Bi(S2CNH2)4·H2O comprises isolated polyhedrons around bismuth (eightfold coordination) linked by hydrogen bonds originating from ammonium, the co‐crystallised water and the dithiocarbamate. In the crystal structure of Bi(S2CNH2)3 exist dimeric aggregates comprising two distorted square antiprisms around bismuth, which are linked together by a common edge. They form infinite double chains with composition [Bi2(S2CNH2)6]∞, which are bridged by N–H···S hydrogen bonds. Evaluation of differential thermal analysis data shows that Bi2S3 develops in the temperature range between 125 and 150 °C, whereas mainly gaseous NH3 and CS2 are emitted during the decomposition reaction.

Tetrameric entity resulting from two distinct dinuclear uranyl-centered motifs bridged through μ2-OH and pyridazine-3,6-dicarboxylate

Abstract The crystal structure of (UO2)4(pdzdc)3(OH)2(H2O)5·11H2O (pdzdc = pyridazine-3,6-dicarboxylate) consists of two distinct dinuclear motifs [(UO2)2N4O11] and [(UO2)2N2O10] with eight-fold and seven-fold coordinations for the uranium centers, respectively. The uranium atoms having the same environment are bridged through a μ2-hydroxo group to each other. The dimeric units are connected to each other through a carboxylate arm from a pdzdc molecule to generate tetranuclear building blocks, which are further assembled into a three-dimensional network by hydrogen bonding. Preliminary investigation of fluorescence property of the complex is presented as well as Raman and Infrared spectroscopies.