Syntheses and Crystal Structures of Ca3Fe2(SeO3)6 and Sr3Fe2(SeO3)6

The new compounds M₃Fe₂(SeO₃)₆ (M = Ca, Sr) were obtained as crystalline precipitates from aqueous solutions of the respective ions, kept in Teflon-coated vessels at a temperature of 227(2)°C for several days. The crystal data are: space group R3 c, a = 8.531(2), 8.802(2) Å; c = 38.89(1), 39.00(1) Å; V = 2451.1, 2616.7 ų, Z = 6. The crystal structures have been refined by single-crystal X-ray diffraction methods to R1 = 0.021, 0.023; wR2 = 0.038, 0.039. The framework structure is built up by two types of FeO₆ octahedra as well as by MO₈ groups and SeO₃ trigonal pyramids by corner- and edge-linkage of the polyhedra.     

Extending the Family of V4+ S=${{ 1/2 }}$ Kagome Antiferromagnets

The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C₃H₅N₂][V₉O₆F₂₄(H₂O)₂] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V⁴⁺ S=${{ 1/2 }}$ ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V⁴⁺, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long‐range magnetic order down to 2 K despite considerable antiferromagnetic exchange.     

K3FeSe3 und K3Fe2Se4, zwei neue Verbindungen im System K/Fe/Se

K₃FeSe₃ and K₃Fe₂Se₄, Two New Compounds in the System K/Fe/Se The two selenides K₃FeSe₃ and K₃Fe₂Se₄ were synthesised by fusion reactions of potassium carbonate with iron and selenium in a stream of hydrogen charged with selenium at 695 °C and 710–730 °C, respectively. The crystal structures were determined by single‐crystal X‐ray diffractometer data. The atomic arrangement of K₃FeSe₃ is characterised by edge sharing [Fe₂Se₆] double tetrahedra separated by potassium ions (space group P2₁/c, Z = 4). The characteristic structural unit of the mixed‐valent compound K₃Fe₂Se₄ is a zig‐zag chain of edge‐sharing, iron‐centred selenium tetrahedra, again separated by potassium ions (space group Pnma, Z = 4).     

Supramolecular Interactions Direct the Formation of Two Structural Polymorphs from One Building Unit in a One‐Pot Synthesis

Two polymorphs of supramolecular isomers, a discrete dimer and a zig‐zag chain, having the same chemical composition, [Mn(Hbit)Cl₂] (Hbit=1‐methyl‐2‐(1H‐1,2,3‐triazol‐4‐yl)‐1H‐benzo[d]imidazole), were obtained solvothermally in a one‐pot synthesis. The isomers differ in a number of ways: orange blocks versus pale‐yellow needles, triclinic P versus orthorhombic Pbcn, double μ₂‐Cl versus alternate single and triple μ₂‐Cl, coordination number 5 versus 6, and antiparallel versus parallel near‐neighbor orientation of Hbit. The packing in each case is driven by the supramolecular interactions, H‐bonds (N?H???Cl, C?H???Cl) and π???π overlaps, calculated to be in the range 20–36 kcal mol^?1. Calculations gave a difference of only 2 kcal mol^?1 in favor of the dimer, which confirms with the observation of principally the dimer at short reaction time. ESI‐MS spectra of the dissolved crystals reveal the same fragments with similar distributions. The presence of two fragments at m/z 286.96 [Mn^IV(Hbit)Cl‐2H]⁺ and 323.94 [Mn^III(Hbit)Cl₂]⁺ indicates that [Mn(Hbit)Cl₂] is the building unit in both cases; thus, the different orientations of the ligands lead to the two polymorphs stabilized by the respective supramolecular interactions. Importantly, the chain form represents the first example with alternate single and triple μ₂‐Cl bridges. The magnetic interactions are weakly antiferromagnetic in both cases, with J in the range 0.07–0.34 cm^?1; however, high‐field EPR analysis reveals moderate magneto‐anisotropy with D=0.26(1) cm^?1, E=0.06(1) cm^?1 and D=0.17(1) cm^?1, E=0.03(1) cm^?1, respectively.     

Pressure‐Induced Enhancement of Magnetic‐Ordering Temperature in an Organic Radical to 70 K: A Magnetostructural Correlation

The structure of the canted antiferromagnet β‐p‐NCC₆F₄CNSSN ( 1 ) was determined from synchrotron powder‐diffraction studies in the pressure range 0–21.6 kbar. Radical 1 crystallizes in the orthorhombic space group Fdd2, but undergoes an asymmetric contraction of the unit‐cell size with increasing pressure. At the molecular level, this contraction of the unit cell is simultaneously accommodated by: 1) an increase in twist angle between aryl and heterocyclic rings; and 2) a shortening of the intermolecular S ??? N contacts, which propagate the magnetic‐exchange pathway. DFT calculations based on the structures in this pressure range revealed an increase in the magnetic‐exchange interaction (J) with increasing pressure, and an excellent correlation was observed between J and the magnetic‐ordering temperature, which increased from 36 K at ambient pressure up to 70 K at 16 kbar.     

Quantitative Assessment of Nanoparticle Single Crystallinity: Palladium‐Catalyzed Splitting of Polycrystalline Metal Oxide Nanoparticles

Crystal gazing : A simple Pd‐catalyzed site‐specific nanoetching method was developed to visualize the polycrystalline nature of Fe₃O₄ (see picture), Fe₂O₃, MnFe₂O₄, CoFe₂O₄, and MnO nanoparticle systems. The technique relies on the very fast etching speed of the grain interface within bi‐ or polycrystalline nanocrystals.

     

Structure of Two Crystal Modifications of Cu(II) trans-Bis-(1,1,1-trifluoro-4-iminopentan-2-onate)

Two crystal modifications of the volatile Cu(II) complex prepared from fluorinated -ketoimine (1,1,1-trifluoro-4-iminopentanon-2-one), CH₃(NH)CCH₂COCF₃, were studied by X-ray crystallography (CAD-4 Enraf-Nonius automatic diffractometer, MoK radiation, graphite monochromator). The phases have molecular structures consisting of trans complexes. In both cases, the square plane around the Cu atom is completed to a tetragonal bipyramid by the carbon atoms of the chelate rings of the neighboring complexes; the Cu...C distance equals 3.36-3.39 . For Cu–O and Cu–N distances, an anomalously large difference between the centrosymmetric and noncentrosymmetric complexes has been found.     

Mild hydrothermal synthesis of the two compounds [SrZn2(SeO3)3] and [SrZn0.68Cu0.32(SeO3)2]: Structural characterization,spectroscopic and magnetic studies

Two new selenite SrZn₂(SeO₃)₃ (1) and SrZn_0.68Cu_0.32(SeO₃)₂ (2) were synthesized by the hydrothermal technique under autogeneous pressure. The crystal structure of both compounds was solved from X-ray diffraction data. Compound (1) was crystallized in P$\overline{1}$ triclinic space group. However, compound (2) was crystallized in P2₁/n monoclinic space group. Infrared studies confirm the presence of all vibration bands in both structures. The temperature dependence of the magnetic susceptibility was measured in the temperature range of 10–300?K at different magnetic field intensities for both compounds. No magnetic properties were detected for compound (1). Mean while, compound (2) displayed antiferromagnetic properties.     

Substitution mechanism and structural study of Ag-doped LiCu2O2

Plate-like stoichiometric crystals of Ag-doped LiCu₂O₂ have been grown by slowly cooling Li₂CO₃·4(1 – x)CuO·4xAgNO₃ (0 ≤ x ≤ 0.5) melts. X-ray single crystal diffraction has shown that the crystals are isostructural with LiCu₂O₂ and contain around 5 at % Ag (relative to the Cu atoms). The addition of silver to lithium cuprate crystals significantly increases their electrical conductivity but has little effect on the temperature behavior of their magnetic moment. The possible substitution mechanism is determined which supports Ag⁺ ↔ Cu⁺, rather than Ag⁺ ↔ Li⁺ in the Ag-doped LiCu₂O₂ crystals.     

Synthesis and crystal structure of EnH<Superscript>2</Superscript>[IrCl<Superscript>6</Superscript>]

The preparation of EnH²[IrCl⁶] is described. Crystal data for C₂H₁₀Cl₆IrN₂ are: a = 6.8972(11) Å, b = 6.9435(16) Å, c = 7.3354(11) Å; α = 88.269(3)°, β = 65.495(2)°, γ = 60.305(2)°, V = 270.76(9) ų, space group P1, Z = 1, d_calc = 2.864 g/cm³. Crystal chemical analysis of the general motif of the structure was performed by the translation sublattice identification technique. It has been found that complex anions [IrCl₆]^2? follow the nodes of a rather regular rhombohedral subcell with the parameters a_c = 7.1 Å, α_c = 64°.     

Synthesis,Crystal and Electronic Structure of Ba_3ZnSb_2O_9 with the 6H-perovskite-type Structure

Crystals of Ba3ZnSb2O9 have been grown by a high-temperature solid-state reaction and characterized by single-crystal X-ray diffraction.Ba3ZnSb2O9 crystallizes in the hexagonal P63/mmc space group with a = 5.8663(4),c = 14.478(2) ,V = 431.49(8) 3,Z = 2 and R(all data) = 0.0167.The structure of Ba3ZnSb2O9 consists of pairs of face-sharing Sb2O9 bi-octahedra connected via corners with two single layers of mutually isolated ZnO6 octahedra.Each Ba2+ ion is bonded to 12 oxygen atoms.The UV-vis absorption spectrum of the compound has been investigated.Additionally,the calculations of band structure and density of states have also been performed with density functional theory method.The obtained results tend to support the experimental data of the absorption spectrum.     

Quantum Spin-1/2 Dimers in a Low-Dimensional Tetrabromocuprate Magnet

This work describes a homometallic spin- tetrabromocuprate adopting a bilayer structure. Magnetic-susceptibility measurements show a broad maximum centred near 70 K, with fits to this data using a Heisenberg model consistent with strong antiferromagnetic coupling between neighbouring copper atoms in different layers of the bilayer. There are further weak intralayer ferromagnetic interactions between copper cations in neighbouring dimers. First-principles calculations are consistent with this, but suggest there is only significant magnetic coupling within one direction of a layer; this would suggest the presence of a spin ladder within the bilayer with antiferromagnetic rung and weaker ferromagnetic rail couplings.     

The First New Hydrogen-Bonded Heterohexanuclear Complex [(salen)Cu]4[(salen)Fe(H2O)2]2(ClO4)2: Molecular and Crystal Structure and Magnetic Properties

The preparation, magnetic properties, and crystal structure of [(salen)Cu]₄[(salen)Fe(H₂O)₂]₂(ClO₄)₂ via hydrogen bonding are described [salen=N,N-ethylenebis (salicylideneiminate)]. Crystals are triclinic, of space group , with cell constants a=12.853(3), b=13.921(3), c=14.251(3) Å, =68.68(3)°, =87.86(3)°, =86.82(3)°, and Z=1. The structure was solved and refined to R=0.064 and R=0.068. The structure comprises the hexanuclear units which result from the linking of four mononuclear fragments [(salen)Cu] and two mononuclear fragment [(salen)Fe(H₂O)]⁺, through Cu -O H -O -Fe -O -H O -Cu hydrogen bonds of coordinating H₂O. In this complex, Fe^III ions are in almost square-planar surroundings. The temperature dependences of the magnetic susceptibilities of the complex have been studied in the 4.2–300 K range, indicating the presence of an antiferromagnetic interactions between metal ions.     

Synthesis and Structural Characterization of a Ruthenium Complex： trans-RuCle（COD）Py2

A new ruthenium complex trans-RuCl2（COD）Py2 has been synthesized and characterized by elemental analysis, IR, IH NMR and single-crystal X-ray diffraction. Crystal data： trans- RuCl2（COD）Py2, Mr = 438.35, monoclinic, space group P21/c, a = 8.9116（9）, b = 14.6175（15）, c = 13.7582（14）A, β = 101.994（1）°, V= 1753.1（3）A^3, Z= 4, Dc= 1.661 g/cm^3, F（000）= 888,μ = 1.199 mm^-1, R = 0.0376 and wR = 0.0789 for 2492 observed reflections with I 〉 2σ（I）.     

Synthesis and Structural Characterization of a Ruthenium Complex:trans-RuCl_2(COD)Py_2

A new ruthenium complex trans-RuCl2(COD)Py2 has been synthesized and charac- terized by elemental analysis, IR, 1H NMR and single-crystal X-ray diffraction. Crystal data: trans- RuCl2(COD)Py2, Mr = 438.35, monoclinic, space group P21/c, a = 8.9116(9), b = 14.6175(15), c = 13.7582(14) , β = 101.994(1)°, V = 1753.1(3) 3, Z = 4, Dc = 1.661 g/cm3 , F(000) = 888, μ = 1.199 mm-1, R = 0.0376 and wR = 0.0789 for 2492 observed reflections with I > 2σ(I).     

Joint Venture of Metal Cluster and Amphiphilic Cationic Minidendron Resulting in Near Infrared Emissive Lamellar Ionic Liquid Crystals

Inorganic red-NIR emissive materials are particularly relevant in many fields like optoelectronic, bioimaging or solar cells. Benefiting from their emission in devices implies their integration in easy-to-handle materials like liquid crystals, whose long-range ordering and self-healing abilities could be exploited and influence emission. Herein, we present red-NIR emissive hybrid materials obtained with phosphorescent octahedral molybdenum cluster anions electrostatically associated with amphiphilic guanidinium minidendrons. Polarized optical microscopy and X-ray analysis show that while the minidendron chloride salts self-organize into columnar phases, their association with the dianionic metal cluster leads to layered phases. Steady-state and time-resolved emission investigations demonstrate the influence of the minidendron alkyl chain length on the phosphorescence of the metal cluster core.     

Synthesis and Crystal Structure of Na2TiO3

The crystal structure of a sodium titanium oxide Na2TiO3 obtained by high temperature solid state reaction method was determined from single-crystal X-ray diffraction study. The compound crystallizes in the monoclinic system, space group C2/c, Mr = 141.88, a = 9.885(1), b = 6.4133(8), c = 5.5048(7) , β = 115.50(3)o, V = 314.99(7) 3, Z = 4, Dc = 2.992 g/cm3, λ = 0.71073 , μ = 27.80 cm–1, F(000) = 272, T = 295 K, R = 0.0189 and wR = 0.0512 for 30 variables and 370 contributing unique reflections. The three-dimensional structure in Na2TiO3 is constructed by the TiO(1)4O(2) and NaO(1)3O(2)2 groups. The titanium atoms are grouped in the form of trigonal bipyramid and arranged along the c axis by sharing the edges. The structure is compared with other structures of related A2BO3 compounds.     

Mechanochemical Synthesis and Nitrogenation of the Nd1.1Fe10CoTi Alloy for Permanent Magnet

In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd_1.1Fe₁₀CoTi compound from Nd₂O₃, Fe₂O₃, Co and TiO₂. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn₁₂-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N₂. The magnetic properties M_r, µ₀H_c, and (BH)_max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were M_r = 75 Am² kg^–1, µ₀H_c = 0.500 T and (BH)_max = 58 kJ·m^–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)_max ~ 114 kJ·m^–3 was obtained for 3 h and the highest µ₀H_c = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.     

Packing motifs and magneto-structural correlations in crystal structures of metallo-tetrakis(1,2,5-thiadiazole)porphyrazine series, MTTDPz (M=H2, Fe, Co, Ni, Cu, Zn)

Single crystals of tetrakis(thiadiazole)porphyrazine and the corresponding metal(II) derivatives, MTTDPz (M=H2, Fe, Co, Ni, Cu, and Zn) were grown by sublimation under reduced pressure with continuous N2 gas flow. Their structures, obtained by X-ray crystallographic analysis, depend significantly on the central metal ion, and the M=Ni and Cu derivatives exhibit polymorphism. They can be classified into three forms, alpha, beta, and gamma. The alpha form (M=H2, Ni, and Cu) is composed of two-dimensional hexagonal close packing formed by side-by-side contacts between thiadiazole rings, whereas the beta form (M=Fe, Co, and Zn) crystallizes into a one-dimensional coordination polymer. The gamma form (M=Ni and Cu) consists of a ladder structure caused by pi stacking, similar to the beta form of phthalocyanine, and by side-by-side contacts between thiadiazole rings. Although the crystal structures of the MTTDPz series exhibited multi-dimensional network structures, magnetic measurements revealed relatively weak exchange interactions, probably reflecting the long distances between the metal ions.