Preparation and characterization of a novel hybrid magnetic semiconductor containing rare, one-dimensional mixed-iodide/chloride anion of lead(II)

A new hybrid inorganic–organic magnetic semiconductor [Ni(bipy)₃Pb₂I_4.84Cl_1.16·DMF]_n (bipy=2,2′-bipyridine) containing novel one-dimensional mixed-halide anion of lead(II) was synthesized by reactions of PbI₂, NaI, NiCl₂ and bipy in DMF solution, and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the space group C2/c with a=29.260(8) Å, b=15.602(4) Å, c=23.695(6) Å, β=126.815(°), Z=8, V=8660(4) Å³ and consists of a magnetic cation [Ni(bipy)₃]²⁺ in addition to one-dimensional mixed-halide anion, which is built up of face-sharing [PbX₆] octahedra. Of the seven crystallographically independent halide sites in this anion, one and five are occupied by Cl and I, respectively, the remaining one has mixed-iodide and -chloride occupancy. The title yellow compound has an optical bandgap of 2.59 eV, and the variable-temperature magnetic susceptibility measurement indicates paramagnetic behavior.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

Tetrameric O–HO hydrogen-bond systems accompanied by C–HO hydrogen-bonds in the crystal of 1,4-bis(hydroxymethyl)triptycene: an X-ray study

The crystal structure of the title compound was determined (crystal data at 143 K: triclinic, space group P−1, Z=4, a=9.538(2) Å, b=11.638(2) Å, c=14.473(2) Å, α=88.647(3)°, β=89.875(3)°, γ=83.835(3)°, V=1596.9(4) ų). In the crystal there exist two kinds of tetrameric O–HO hydrogen-bond (H-bond) systems that are quite similar to each other. The oxygen atoms accept also intermolecular C–HO H-bonds. The two types of the H-bonds connect the molecules to an infinite two-dimensional supramolecular unit, the stacking of which is aided by an intermolecular C–Hπ H-bond. A phase transition with ΔH_t=4.4±0.1 kJ/mol was found at around 420 K.     

Molybdenum(VI) network polymers based on anion–π interaction and hydrogen bonding: Synthesis, crystal structures and oxidation catalytic application

A crystallographic investigation of anion–π interactions and hydrogen bonds on the preferred structural motifs of molybdenum(VI) complexes has been carried out. Two molybdenum(VI) network polymers MoO₂F₄·(Hinca)₂ (1) and MoO₂F₃(H₂O)·(Hinpa) (2), where inca = isonicotinamide and inpa = isonipecotamide, have been synthesized, crystallographically characterized and successfully applied to alcohol oxidation reaction. Complex 1 crystallizes in the monoclinic space C2/c: a = 16.832(3) Å, b = 8.8189(15) Å, c = 12.568(2) Å, β = 118.929(3)°, V = 1560.1(5) Å³, Z = 4. Complex 2 crystallizes in the triclinic space P-1: a = 5.459(2) Å, b = 9.189(4) Å, c = 12.204(5) Å, α = 71.341(6)°, β = 81.712(7)°, γ = 77.705(7)°, V = 564.8(4) Å³, Z = 2. Complex 1 consists of hydrogen bonding and anion–π interactions, both of which are considered as important factors for controlling the geometric features and packing characteristics of the crystal structure. The geometry of the sandwich complex of [MoO₂F₄]²⁻ with two pyridine rings indicates that the anion–π interaction is an additive and provides a base for the design and synthesis of new complexes. For complex 2, the anions and the protonated inpa ligands form a 2D supramolecular network by four different types of hydrogen contacts (N–HF, N–HO, O–HF and O–HO). The catalytic ability of complexes 1 and 2 has also been evaluated by applying them to the oxidation of benzyl alcohol with TBHP as oxidant.     

A manganese sulfite with extended metal–oxygen–metal bonds exhibiting hydrogen uptake

A manganese sulfite of the formula Mn₅(OH)₄(SO₃)₃·2H₂O, I{a=7.5759(7) Å, b=8.4749(8) Å, c=10.852(1) Å, β=100.732(2)°, Z=2, space group=P2₁/m (no. 11), R₁=0.0399 and wR₂=0.1121 [for R indexes I>2σ(I)]}, comprising Mn₃O₁₄ units and extended Mn–O–Mn bonds along the three dimensions has been synthesized under hydrothermal conditions. It has narrow channels along the b-axis and exhibits hydrogen storage of 2.1 wt% at 300 K and 134 bar.     

Syntheses, crystal structures and optical properties of the first strontium selenium(IV) and tellurium(IV) oxychlorides: Sr3(SeO3)(Se2O5)Cl2 and Sr4(Te3O8)Cl4

Two new quaternary strontium selenium(IV) and tellurium(IV) oxychlorides, namely, Sr₃(SeO₃)(Se₂O₅)Cl₂ and Sr₄(Te₃O₈)Cl₄, have been prepared by solid-state reaction. Sr₃(SeO₃)(Se₂O₅)Cl₂ features a three-dimensional (3D) network structure constructed from strontium(II) interconnected by Cl⁻, SeO₃²⁻ as well as Se₂O₅²⁻ anions. The structure of Sr₄(Te₃O₈)Cl₄ features a 3D network in which the strontium tellurium oxide slabs are interconnected by bridging Cl⁻ anions. The diffuse reflectance spectrum measurements and results of the electronic band structure calculations indicate that both compounds are wide band-gap semiconductors.     

Formation of helix-containing rods in a hybrid inorganic–organic material

The novel aluminum ethylenediphosphonate fluoride, [HN(CH₂CH₂NH₃)₃][Al₂(O₃PCH₂CH₂PO₃)₂F₂]·H₂O (1) (monoclinic, P2₁/n, a=12.145(4) Å, b=9.265(3) Å, c=20.422(6) Å, β=104.952(4)°, Z=3, R₁=0.092, wR₂=0.196) has been synthesized by solvothermal methods in the presence of tris(2-aminoethyl)amine and its structure determined using single microcrystal X-ray diffraction data. Compound 1 is a one-dimensional extended chain structure composed of well-separated anionic [Al₂(O₃PCH₂CH₂PO₃)₂F₂]⁴⁻ rods containing helical chains of corner-shared cis-AlO₄F₂ octahedra at their core. The charge-compensating tris(2-aminoethyl)ammonium cations separate the anionic [Al₂(O₃PCH₂CH₂PO₃)₂F₂]⁴⁻ rods that contain either left- or right-handed helical chains. The incorporation of the organic components into this hybrid material has aided the adoption of one-dimensionality by the compound and defined the pitch of the helical AlO₄F chain.     

Syntheses, crystal structures and spectroscopic properties of KEu[AsS4], K3Dy[AsS4]2 and Rb4Nd0.67[AsS4]2

Three rare earth compounds, KEu[AsS₄] (1), K₃Dy[AsS₄]₂ (2), and Rb₄Nd_0.67[AsS₄]₂ (3) have been synthesized employing the molten flux method. The reactions of A₂S₃ (A = K, Rb), Ln (Ln = Eu, Dy, Nd), As₂S₃, S were accomplished at 600 °C for 96 h in evacuated fused silica ampoules. Crystal data for these compounds are: 1, monoclinic, space group P2₁/m (no. 11), a = 6.7276(7) Å, b = 6.7190(5) Å, c = 8.6947(9) Å, β = 107.287(12)°, Z = 2; 2, monoclinic, space group C2/c (no. 15), a = 10.3381(7) Å, b = 18.7439(12) Å, c = 8.8185(6) Å, β = 117.060(7)°, Z = 4; 3, orthorhombic, space group Ibam (no. 72), a = 18.7333(15) Å, b = 9.1461(5) Å, c = 10.2060(6) Å, Z = 4. 1 is a two-dimensional structure with ²_∞[Eu(AsS₄)]⁻ layers separated by potassium cations. Within each layer, distorted bicapped trigonal [EuS₈] prisms are linked through distorted [AsS₄]³⁻ tetrahedra. Each Eu²⁺ cation is coordinated by two [AsS₄]³⁻ units by edge-sharing and bonded to further two [AsS₄]³⁻ units by corner-sharing. Compound 2 contains a one-dimensional structure with ¹_∞[Dy(AsS₄)₂]³⁻ chains separated by potassium cations. Within each chain, distorted bicapped trigonal prisms of [DyS₈] are linked by slightly distorted [AsS₄]³⁻ tetrahedra. Each Dy³⁺ ion is surrounded by four [AsS₄]³⁻ moieties in an edge-sharing fashion. For compound 3 also a one-dimensional structure with ¹_∞[Nd₀.₆₇(AsS₄)₂]⁴⁻ chains is observed. But the Nd position is only partially occupied and overall every third Nd atom is missing along the chain. This cuts the infinite chains into short dimers containing two bridging [As₄]³⁻ units and four terminal [AsS₄]³⁻ groups. 1 is characterized with UV/vis diffuse reflectance spectroscopy, IR, and Raman spectra.     

Self-assembly of two novel bisupporting Keggin-polyoxometalate derivatives: Hydrothermal synthesis and structure characterization of (X = P, m = 1; X = Si, m = 2)

Two novel organic–inorganic hybrid polyoxometalates, (X = P, m = 1 1; X = Si, m = 2 2; 2,2′-bpy = 2,2′-bpyridine), have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. They are isostructural, possessing orthorhombic, and the parameters of unit cells for compound 1 are space group Pbca, a = 17.317(4) Å, b = 17.092(3) Å, c = 20.587(4) Å, V = 6445(2) Å³, Z = 4; for compound 2 are space group Pcab, a = 17.181(3) Å, b = 18.198(4) Å, c = 20.672(4) Å, V = 6463(2) Å³, Z = 4. The two compounds show a layer framework constructed from Keggin-polyoxoanion clusters and [Cu (2, 2′-bpy)₂]²⁺ coordination polymer fragments via weak covalent interactions, resulting in a 3D network via supramolecular interactions. Their electrochemical properties are studied in detail.     

Crystal structure and IR spectrum of 1-O-α- -glucopyranosyl- -mannitol–ethanol (2/1)

1-O-α- -Glucopyranosyl- -mannitol–ethanol (2/1), (C₁₂H₂₄O₁₁)₂–C₂H₅OH, crystallizes in the monoclinic space group P2₁ with unit cell dimensions a=11.4230(8) Å, b=9.525(4) Å, c=15.854(2) Å, β=102.751(7)° and V=1682.4(7) ų, Z=2, D_x=1.45 Mg m⁻³, λ (Mo-K_α)=0.71069 Å, μ=0.128 mm⁻¹, F(000)=788 and T=293(2) K. The structure was solved by direct methods and refined by least-squares calculations on F² to R₁=0.0371[I>2σ(I)], and 0.0930 (all data, 3542 independent reflections, R_int=0.021). There are two molecules of glucopyranosylmannitol (GPM) and one ethanol molecule in the asymmetric unit, and the glucopyranosyl ring adopts a chair conformation in both GPM molecules. Bond lengths and angles accord well with the mean values of related structures. The conformation along the mannitol side chain for one of the GPM molecules was the same as for the known polymorphs of -mannitol, while the conformation of the other molecule was different, indicating different conformational arrangements in the terminal carbon atoms of the mannitol side chains of the two GPM molecules. The structure in 1-O-α- -glucopyranosyl- -mannitol–ethanol (2/1) is held together by a very complex hydrogen bonding system, which consists of an infinte chain propagating along the b-axis and a discontinuous chain, which binds the ethanol molecule to the structure. The FTIR spectra for anhydrous GPM, GPM dihydrate and GPM–ethanol (2/1) were recorded. Both IR and X-ray results indicate the extensive hydrogen bonding in crystalline state.     

Phases in the Al–Yb–Zn system between 25 and 50 at% ytterbium

Phases YbZn_1−xAl_x, YbZn_2−xAl_x and YbZn_3−xAl_x were studied by electron microprobe analysis and X-ray single crystal and powder methods. The compound YbZn_0.8Al_0.2 crystallizes with the CsCl-type, a=3.635(2) Å. Four phases were investigated by single crystal X-ray diffraction: YbZn_0.996(6)Al_1.004(6), MgNi₂-type, P6₃/mmc, a=5.573(1), c=18.051(3) Å, Z=8, wR2=0.040 and YbZn_0.88(3)Al_1.12(3), MgCu₂-type, , a=7.860(2) Å, Z=8, wR2=0.060, both showing mixed Zn/Al occupancy; YbZn_2.50(1)Al_0.50(1), CeNi₃-type, P6₃/mmc, a=5.496(1), c=17.336(2) Å, Z=6, wR2=0.036 and YbZn_1.92(2)Al_1.08(2), PuNi₃- or NbBe₃-type, , a=5.499(1), c=26.134(5) Å, Z=9, wR2=0.053, where the zinc atoms are ordered in the CaCu₅ segment, while share the sites with aluminium in the Laves phase segment. In the pseudobinary section YbZn_2−xAl_x four structures occur in sequence with increasing the electron concentration: CeCu₂ or KHg₂ (x=0–0.3), MgZn₂ (x=0.33–0.54), MgNi₂ (x=0.68–1.01) and MgCu₂ (x=1.12–2). This sequence agrees with the results of first-principles calculations, already reported in the literature for other similar series. In the YbZn_3−xAl_x section CeNi₃-type compounds occur with x=0.40–0.88 followed by PuNi₃-type compounds with x=0.92–1.10. The stability ranges of these phases are related to the valence electron concentration.     

New mixed-halide, boron-centered zirconium cluster phases with different cation distributions within a cluster framework: syntheses and structures of A[(Zr6B)ClxI14−x] (A=Na or Cs, 0x4)

Two new mixed-halide zirconium cluster phases have been synthesized by solid-state reactions in sealed tantalum containers from the Zr(IV) halides, elemental Zr and B, and NaI or CsCl, respectively. Single-crystal X-ray data were used to determine the crystal structures of Na[(Zr₆B)Cl_3.9I_10.1], and Cs[(Zr₆B)Cl_2.2I_11.8]. Both phases crystallize in a stuffed version of the [Nb₆Cl₁₄] structure type, orthorhombic, space group Cmca (Na[(Zr₆B)Cl_3.87(5)I_10.13]: a=15.787(2) Å, b=14.109(2) Å, c=12.505(2) Å, Z=4, R1(F)=0.0322 and wR2(F²)=0.0842; Cs[(Zr₆B)Cl_2.16(5)I_11.84]: a=15.696(4) Å, b=14.156(4) Å, c=12.811(4) Å, Z=4, R1(F)=0.0404 and wR2(F²)=0.1031). This structure type is constructed of clusters which contain centered (Zr₆Z) octahedra of the type [(Zr₆Z)X₁₂ⁱX₆^a] with Z=B and X=Cl and/or I. In both structures, chlorine and iodine atoms are randomly (to X-rays) distributed on the inner non-cluster-interconnecting ligand positions, whereas those sites which bridge metal octahedra are solely occupied by iodine. The phase widths for both phases have been found to cover 0x4 for A^I[(Zr₆B)Cl_xI_14−x]. Whereas the sodium cations in Na[(Zr₆B)Cl_xI_14−x] occupy 25% of a site which is octahedrally surrounded by halogen atoms, the larger cations in the cesium-containing phase occupy a 12-coordinate site within the cluster network.     

Comparative evolved gas analytical and structural study on trans-diammine-bis(nitrito)-palladium(II) and platinum(II) by TG/DTA–MS, TG–FTIR, and single crystal X-ray diffraction

Detailed study on identification and thermal decomposition of solid title compounds 1 and 2 crystallized from the used aqueous ammonia solutions of Pd(NH₃)₂(NO₂)₂ and Pt(NH₃)₂(NO₂)₂, has been carried out. Beyond the composition of complexes 1 and 2, their trans square planar configuration have already been recognized by reference IR spectra and powder XRD patterns, nevertheless their exact molecular and crystal structure as of trans-Pd(NH₃)₂(NO₂)₂ (1, Pd-NN) and trans-Pt(NH₃)₂(NO₂)₂ (2, Pt-NN) has been determined by single crystal X-ray diffraction (R = 0.0515 and 0.0341), respectively. Despite their compositional and configuration analogy, they crystallize in different crystal systems and space groups. The crystals of 1 (Pd-NN) are triclinic (space group No. 2, P-1, a = 5.003(1) Å, b = 5.419(1) Å, c = 6.317(1) Å, α = 91.34(2)°, β = 111.890(10)°, γ = 100.380(10)°), while those of 2 (Pt-NN) are monoclinic (space group No. 5, C2, a = 7.4235(16) Å, b = 9.130(2) Å, c = 4.4847(10) Å, β = 99.405(7)°).The pyrolytic processes of 1 and 2 (which might be sensitive to shock and heat) have been followed by simultaneous thermogravimetric and differential thermal analysis (TG/DTA), while the evolved gaseous species have been traced in situ by online coupled TG/DTA–EGA–MS and TG–EGA–FTIR instruments in He and air. Pd and Pt powders, forming as final solid products in single step, are captured and checked by TG and XRD. Whilst the unified evolved gas analyses report evolution of N₂, H₂O, NH₃, N₂O, NO, and NO₂ gases as gaseous product components in the exothermic decomposition of both trans-Pd(NH₃)₂(NO₂)₂ (1) and trans-Pt(NH₃)₂(NO₂)₂ (2) starting from ca. 230 and 220 °C, in sealed crucibles with a pinhole on the top, respectively.     

The crystal and molecular structure of potassium aquapentachloroiridate(III) and the H, C, N NMR coordination shifts in iridium(III) chloride complexes with 2,2′-bipyridine or 1,10-phenanthroline

The crystal and molecular structure of potassium aquapentachloroiridate(III) (K₂[Ir(H₂O)Cl₅]) was reported. The [Ir(H₂O)Cl₅]²⁻ anions are nearly octahedral, the axial Ir–Cl bond (2.322(2) Å) being shorter than the equatorial ones (2.346(2)–2.360(2) Å); the Ir–O bond length is 2.090(4) Å. Ir(III) chloride complexes with 2,2′-bipyridine (LL = bpy) or 1,10-phenanthroline (LL = phen), of the general formulae K[Ir(LL)Cl₄] and cis-[Ir(LL)₂Cl₂]Cl, were studied by far-IR and ¹H–¹³C, ¹H–¹⁵N HMBC/HMQC/HSQC–NMR. High-frequency ¹H NMR coordination shifts (Δ^1H_coord = δ^1H_complex − δ^1H_ligand; max. ca. +1 ppm) were noted for [Ir(LL)Cl₄]⁻ anions, while for cis-[Ir(LL)₂Cl₂]⁺ cations they had variable sign and magnitude (max. ca. ±1 ppm); they were dependent on the proton position, being mostly expressed for the nitrogen-adjacent hydrogens (H(6) for bpy, H(2) for phen). ¹³C NMR signals were high-frequency shifted (by max. ca. 8 ppm), whereas all ¹⁵N nuclei were shifted to the lower frequency (by ca. 105–120 ppm). The experimental ¹H, ¹³C, ¹⁵N NMR chemical shifts were reproduced by semi-empirical quantum-chemical calculations (B3LYP/LanL2DZ+6-31G^**//B3LYP/LanL2DZ+6-31G*).     

Flux synthesis of (3,4)-connected zinc phosphites with different framework topologies

Two three-dimensional open-framework zinc phosphites, H₂aem·Zn₃(HPO₃)₄·0.5H₂O (1) and H₂apm·Zn₃(HPO₃)₄ (2), have been synthesized by a phosphorous acid flux method, where aem=4-(2-aminoethyl)morpholine and apm=4-(3-aminopropyl)morpholine. Compound 1 crystallizes in the monoclinic system, P2₁/c, a=9.5852(7) Å, b=20.3941(8) Å, c=10.5339(8) Å, β=94.125(9)°, V=2053.8(2) Å³, Z=4, R₁=0.0319, wR₂=0.0628. Compound 2 crystallizes in the monoclinic system, P2₁/n, a=8.589(2) Å, b=14.020(3) Å, c=16.606(3) Å, β=97.190(8)°, V=1983.9(7) Å³, Z=4, R₁=0.0692, wR₂=0.1479. Both compounds are based on (3,4)-connected networks with 8- and 12-ring channels, which are constructed from Zn₃(HPO₃)₄ clusters as the same secondary building units. These inorganic clusters are spatially organized by different structure-directing agents into different three-dimensional frameworks.     

Diazabicyclo[2.2.2]octane-1,4-diium occluded in cubic anionic coordinated framework: the role of trifurcated hydrogen bonds of N–HO and C–HO

A unique coordinated molecular capsule compound is synthesized and characterized by X-ray diffraction. The compound crystallizes in cubic space group of Pa-3 with a=14.348(1), b=14.348(1), c=14.348(1) Å, V=2953.8(4) ų, Z=8. The diazabicyclo[2.2.2]octane-1,4-diium is occluded in the cubic anionic coordinated framework of K⁺ and (ClO₄)⁻ in a dimension of 7.174(1) Å, and assumes ordered feature. All of hydrogen atoms take parts in trifurcated hydrogen bonds of N–HO and C–HO type, respectively, the later being reported for the first time. The IR spectrum of the title compound shows significant shift of CH₂ vibrational bands, and are correlated with X-ray structural data.     

Synthesis, crystal structures, phase transition characterization and thermal decomposition of a new dabcodiium hexaaquairon(II) bis(sulfate): (C6H14N2)[Fe(H2O)6](SO4)2

The crystal structures of 1,4-diazabicyclo[2.2.2]octane (dabco)-templated iron sulfate, (C₆H₁₄N₂)[Fe(H₂O)₆](SO₄)₂, were determined at room temperature and at −173 °C from single-crystal X-ray diffraction. At 20 °C, it crystallises in the monoclinic symmetry, centrosymmetric space group P2₁/n, Z=2, a=7.964(5), b=9.100(5), c=12.065(5) Å, β=95.426(5)° and V=870.5(8) ų. The structure consists of [Fe(H₂O)₆]²⁺ and disordered (C₆H₁₄N₂)²⁺ cations and (SO₄)²⁻ anions connected together by an extensive three-dimensional H-bond network. The title compound undergoes a reversible phase transition of the first-order at −2.3 °C, characterized by DSC, dielectric measurement and optical observations, that suggests a relaxor–ferroelectric behavior. Below the transition temperature, the compound crystallizes in the monoclinic system, non-centrosymmetric space group Cc, with eight times the volume of the ambient phase: a=15.883(3), b=36.409(7), c=13.747(3) Å, β=120.2304(8)°, Z=16 and V=6868.7(2) ų. The organic moiety is then fully ordered within a supramolecular structure. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the iron oxide.     

The crystal structure, vibrational spectra, and thermal behavior of dilithium piperazinium(2+) selenate tetrahydrate and dilithium N,N′-dimethylpiperazinium(2+) selenate tetrahydrate

The crystal structure of dilithium piperazinium(2+) selenate tetrahydrate has been solved; this substance crystallizes in the triclinic space group , a=7.931(2) Å, b=7.974(2) Å, c=7.991(2) Å, α=106.99(2)°, β=101.83(2)°, γ=119.28(2)° Z=1, R=0.0280 for 1489 observed reflections. A similar compound, dilithium N,N′-dimethylpiperazinium(2+) selenate tetrahydrate crystallizes in a monoclinic system with space group P2₁/c and lattice parameters a=7.338(1) Å, b=8.792(2) Å, c=12.856(1) Å, β=92.04(2)°, Z=2, R=0.0334 for 1462 observed reflections. Both structures are centrosymmetric with center of symmetry in the center of eight membered ring formed with two SeO₄ tetrahedra and two LiO₄ tetrahedra connected through tops. The two remaining oxygens on each Li atom come from water molecules. The FTIR and FT Raman spectra of both natural and N,O-deuterated substances have been measured and studied. The thermoanalytical properties were studied using TG, DTG and DTA methods in the temperature range 293–873 K for piperazinium derivative and in the range 293–523 K for dimethylpiperazinium derivative. DSC measurements were carried out in the temperature range 95–343 K. No phase transition was found in this temperature region for either of the compounds.     

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Exploratory synthesis in the K–In–Ge–As system has yielded the unusual layered compounds K₈In₈Ge₅As₁₇(1) and K₅In₅Ge₅As₁₄(2), both of which contain In–Ge–As layers with interleaved potassium ions, Ge–Ge bonds, InAs₄tetrahedra, As–As bonds, and rows of Ge₂As₆dimers. Compound 1 has As₃groups, while compound 2 has infinite As ribbons on both faces of each layer. Unlike compound 1, compound 2 has substitutional defects where indium partially occupies each of the three independent germanium sites in the ratio of 1:5 for In:Ge. This partial occupancy makes 2 an electron-precise compound. The Ge(In)–Ge(In) bond of 2 is longer than the Ge–Ge bond of 1, and this bond lengthening effect was confirmed by performing DFT-MO calculations on the model compounds H₃Ge–GeH₃and H₃Ge–InH⁻₃. Possible implications of electron imprecise formulas determined by X-ray crystal structure determinations are discussed. Compound 1: space groupP2₁/cwitha=18.394 (8) Å,b=19.087 (7) Å,c=25.360 (3) Å,β=105.71 (2)°,V=8571 (4) ų, andD_calcd=4.45g/cm³forZ=4. Refinement on 4455 reflections yieldedR(R_w)=6.8%(7.8%). Compound 2: space groupC2/mwitha=40.00 (1) Å,b=3.925 (2) Å,c=10.299 (3),β=99.97 (2)°,V=1592 (1) ų, andD_calcd= 4.55g/cm³forZ=8. Refinement on 1206 reflections yieldedR(R_w)=5.6% (5.7%).     

Investigation on the complex of diperoxovanadate with picolinamide

A novel diperoxovanadate complex NH₄[OV(O₂)₂(picolinamide)]·H₂O was synthesized from aqueous solution under physiological conditions. The solution structure of the complex was characterized by multinuclear (¹H, ¹³C, ¹⁴N, and ⁵¹V), variable temperature as well as two-dimensional (DOSY) NMR techniques in the interaction system of NH₄VO₃/H₂O₂/picolinamide at room temperature. The crystal structure of the complex was determined at 223 K by single-crystal X-ray diffraction method. It belongs to the monoclinic space group P21/c with a = 7.323(3) Å, b = 14.255(7) Å, c = 10.022(5) Å, β = 99.524(9)°, V = 1031.7(8) Å³, and Z = 4. The crystal is composed of ammonium ions, picolinamide oxodiperoxovanadate(V) ions, and water molecules, which are held together by ionic and hydrogen bond forces. The species [OV(O₂)₂(picolinamide)]⁻ is seven-coordinated with a distorted pentagonal bipyramidal geometry both in solution and in crystal.