Inorganic Chemistry II

Angular structure of 3,3′,5,5′-tetramethyl-4,4′-bipyrazole tecton (Me4bpz) supports multiple helical strands in a series of coordination and hydrogen bonded polymers prepared using hydrothermal technique. Compounds reveal a variety of helical architectures and exist in the forms of double helicate Ag(Me4bpz)(PO2F2), two-dimensional network formed by inter-connection of the helices Ag2(Me4bpz)3(CF3CO2)2, interpenetrated two-dimensional networks by interconnection of double helices Ag4(Me4bpz)5(NO3)4 · 2H2O and triple helicate formed by NH‒‒‒N hydrogen bonded bipyrazole molecules in structure Me4bpz·H2O.Coordination polymers Ag(Me4bpz)X ((X = ClO4−, CF3SO3−, C2F5CO2−) adopt simpler chain-like structure. In all coordination compounds the bipyrazole acts as a bridging neutral group and connects two silver atoms at the distances of 9.44–9.94Å.

Diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) measurements (4000-1500 cm -1 ) and the results of neutron powder diffraction have been combined to study the structure of adsorption complexes of water in a NaX zeolite at different water loadings (25, 48, 72, and 120 water molecules per unit cell, respectively). Sharp bands corresponding to non-hydrogen-bonded OH groups of water molecules and broad associate bands due to hydrogen-bonded molecules are observed in the DRIFT spectra. We observe a remarkable downshift of the high-frequency associate band in a narrow temperature interval when the water amount decreases from 120 to 72 molecules per unit cell, which could signify some kind of "phase transition" for the water inside the zeolite cavities. Neutron powder diffraction results show that water molecules are predominantly localized in or near the 12-ring windows. Water molecules with hydrogen-bonded and non-hydrogen-bonded OH groups were found, in agreement with the observation of sharp and broad bands in the DRIFT spectra. We find strong evidence for the formation of cyclic hexamers of water molecules localized in the 12-ring windows, which are further stabilized by hydrogen bonds to framework oxygen atoms.

The aromatic thioether (2,6-bis((2-(dimethylamino)ethylamino)methyl)phenyl)(tert-butyl)sulfane (6) reacts with [Pd(NCCH 3 ) 2 Cl 2 ] under S-C bond cleavage to give the dinuclear palladium(II) complex [L 3 Pd 2 (l-Cl)] 2+ (7), where (L 3 ) À = 2,6-bis((2-(dimethylamino)ethylamino)methyl)-thiophenolate. Complex 7 reacts readily with sodium acetate and sodium acetamide by the displacement of the bridging chloride group forming [L 3 Pd 2 (l-OAc)] 2+ (8) and [L 3 Pd 2 (l-ONHCCH 3 )] 2+ (9), respectively. Complex 8 can also be prepared by the reaction of 6 with [Pd(OAc) 2 ]. All complexes were isolated as perchlorate salts and fully characterized by ESI-MS, IR, 1 H, and 13 C NMR spectroscopy. The structures of 7[ClO 4 ] and 9[ClO 4 ] 2 have been determined by X-ray crystallography. The latter structure reveals a l 1,3bridging acetamidate unit showing that (L 3 ) À can alter its conformation sufficiently to accommodate a multi-atom bridging species between the two Pd atoms.

Application of high-pressure high-temperature conditions (3.5 GPa at 1673 K for 5 h) to mixtures of the elements (RE:B:S ¼ 1:3:6) yielded crystalline samples of the isotypic rare earth-thioborate-sulfides RE 9 [BS 3 ] 2 [BS 4 ] 3 S 3 , (RE ¼ Dy-Lu), which crystallize in space group P6 3 (Z¼ 2/3) and adopt the Ce 6 Al 3.33 S 14 structure type. The crystal structures were refined from X-ray powder diffraction data by applying the Rietveld method. Dy: a¼ 9.4044(2)Å, c¼ 5.8855(3)Å; Ho:

The isotypic rare earth thioborate sulfides, RE 9 [BS 3 ] 2 [BS 4 ] 3 S 3 (RE = Dy -Lu) [1], were obtained under high-pressure hightemperature conditions [2] (3.5 GPa, 1673 K, 5 h) by using molar ratios 1:3:6 of RE metal, amorphous boron and sulfur as the starting mixtures. Their crystal structures were refined from X-ray powder diffraction. RE 9 [BS 3 ] 2 [BS 4 ] 3 S 3 crystallize in space group P6 3 (Z = 2/3) and adopt the Ce 6 Al 3.33 S 14 structure type [3] (Dy: a = 9.4044(2) Å, c = 5.8855(3) Å; Ho: a = 9.3703(1) Å, c = 5.8826(1) Å; Er: a = 9.3279(12) Å, c = 5.8793(8) Å; Tm: a = 9.2869(3) Å, c = 5.8781(3) Å; Yb: a = 9.2514(5) Å, c = 5.8805(6) Å; Lu: a = 9.2162(3) Å, c = 5.8911(3) Å). An interesting feature in the crystal structure is given by the presence of [BS 3 ] 3and [BS 4 ] 5ions, as well as a [S 3 ] 6substructure, which are analyzed by means of Xray diffraction, quantum mechanical calculations and chemical bonding analysis carried out on 1 1 3 supercells of Lu 9 [BS 3 ] 2 [BS 4 ] 3 S 3 .

The title compounds are prepared by high temperature/high pressure reactions of mixtures of the elements in the molar ratio RE:B:S = 1:3:6 (3.5 GPa, 1673 K, 5 h). The products are characterized by powder XRD, SEM, XAS, and DFT electronic structure calculations. The compounds crystallize isotypically in the space group P6 3 with Z = 2/3 (Ce 6 Al 3.33 S 14 -type structure). The structure contains trigonal planar [BS 3 ] 3-, tetrahedral [BS 4 ] 5-, as well as [ (S 2-) 3 ] units (❐ : vacant boron site). The vacancies are located at the trigonal planar coordinated boron sites. -(BORNA, M.; HUNGER, J.; ORMECI, A.; ZAHN, D.; BURKHARDT, U.; CARRILLO-CABRERA, W.; CARDOSO-GIL, R.; KNIEP*, R.; J. Solid State Chem. 184 (2011) 2, 296-303, http://dx.

β-Ca3N2, a Metastable Nitride in the System Ca-N. -Metastable β-Ca3N2 (prepared by reaction of the elements at 700 K or by reaction of Ca 2 N with N 2 at 500 K) is characterized by powder XRD, neutron diffraction, magnetic susceptibility and electrical resistivity measurements, and by DFT calculations. β-Ca3N2 crystallizes in the rhombohedral space group R3c isotypically to α-Al2O3. The structure contains a network of NCa6 octahedra that share common faces and edges. β-Ca3N2 is a diamagnetic semiconductor which transforms monotropically to cubic α-Ca 3 N 2 at ≈810 K. -(HOEHN*, P.; HOFFMANN, S.; HUNGER, J.; LEONI, S.; NITSCHE, F.; SCHNELLE, W.; KNIEP, R.; Chem. Eur. J. 15 (2009) 14, 3419-3425; MPI Chem. Phys. fester Stoffe,

The Al-Mg-Zn system has been investigated frequently due to its importance for the development of light and high strength Al-based alloys. A primitive icosahedral quasicrystalline phase (q), a 1/1- and 2/1-Fibonacci approximant (τ1,τ2) and the orthorhombic φ-phase form as ternary phases. The crystal structure and the homogeneity range of the τ1-phase are well known, whereas the published data on structure and composition for the q and the τ2 phase of three different investigations are inconsistent. Takeuchi [1] and later Spiekermann [2] report the composition Al15Mg43Zn42 for the τ2-phase. According to an investigation by Sugijama [3] the τ2 phase forms with less Zn content at Al17Mg46Zn37 and the most recent investigation by Lin et al. [4] claims that the composition is more Zn rich at Al13Mg32Zn55. All samples have been obtained by annealing at 360 °C by the authors. The objective of this work is to find the true compositional stability range of the 2/1-approximant. Alloys were pr...

BS 3 Sm, orthorhombic, Pna2 1 (no. 33), a = 7.3657(5) Å, b = 6.0272(2) Å, c = 8.8004(6) Å, V = 390.69 Å 3 , Z = 4, R(F 2 ) = 0.068, R(P) = 0.013, T = 295 K. Sm[BS 3] was prepared by using a high-temperature highpressure route. Molar ratios of 1 : 3 : 6 of samarium (powder, ChemPur, 99.9 %), amorphous boron (ABCR, 99 %) and sulfur (Alfa Aesar, 99.9995 %, sublimed under vacuum to reduce contamination by oxygen below 1 %) were used. Molar ratios corresponding to the chemical composition of the title compound did not yield sufficiently pure materials. The educts were ground and filled into the assembly of the octahedral high pressure setup, under argon atmosphere of a glove box. Hexagonal boron nitride was used as the crucible material. High pressure conditions were achieved by using a hydraulic uniaxial press [1]. Force redistribution was accomplished by a Walker-type module and MgO octahedra with an edge length of 18 mm . Elevated temperatures were realized by resistive heating of graphite tubes enclosing the sample crucible. For the synthesis of Sm[BS 3], the assembly was heated to 1673 K and compressed to 3 GPa for 5 h. After the pressure and heating cycle, the arrangement was instan-

Am ixture of 779.01 mg (5.528 mmol) praseodymium powder (ChemPur, 99.9 %), 298.90 mg (27.648 mmol) amorphous boron (powder, ABCR, 99 %) and 1595.66 mg (49.762 mmol) sulfur (Alfa Aesar, 99.9995 %, sublimed under vacuum to reduce oxygen contamination below 1%)was ground, cold pressed, again ground and filled in aboron nitride crucible (diameter 16/10 mm, height 50 mm). The crucible was deposited in asealed tantalum

2-Oxo-D-gluconic acid obtained by fermentation of D-glucose was used as starting material for syntheses of amino acids. We trapped the carbohydrate in its furanoid configuration and synthesized an αand an ω-amino acid. After deprotection of the hydroxyl groups the latter did not isomerize to the substituted piperidine (aza-sugar) as expected, but remained in the furanose form. The starting structure 2 was proven by crystal structure analysis. The conformational identification of the other substances was done by NMR measurements following known rules for furanoses.

Application of high-pressure high-temperature conditions (3.5 GPa at 1673 K for 5 h) to mixtures of the elements ( RE:B:S=1:3:6) yielded crystalline samples of the isotypic rare earth-thioborate-sulfides RE9[BS 3] 2[BS 4] 3S 3, ( RE=Dy-Lu), which crystallize in space group P6 3 ( Z=2/3) and adopt the Ce 6Al 3.33S 14 structure type. The crystal structures were refined from X-ray powder diffraction data by applying the Rietveld method. Dy: a=9.4044(2) Å, c=5.8855(3) Å; Ho: a=9.3703(1) Å, c=5.8826(1) Å; Er: a=9.3279(12) Å, c=5.8793(8) Å; Tm: a=9.2869(3) Å, c=5.8781(3) Å; Yb: a=9.2514(5) Å, c=5.8805(6) Å; Lu: a=9.2162(3) Å, c=5.8911(3) Å. The crystal structure is characterized by the presence of two isolated complex ions [BS 3] 3- and [BS 4] 5- as well as [□(S 2-) 3] units.

The reaction of Fe(NO3)3∙9 H2O with KOH under hydroflux<br>conditions at about 200 °C produces red crystals of K2−xFe4O7 in a quantitative yield. In the crystal structure, edge-sharing [FeO6]<br>octahedra form [ ∞Fe2O6] honeycomb nets. Pillars consisting of pairs of vertex-sharing [FeO4] tetrahedra link the honeycomb layers and form columnar halls in which the potassium ions are located. The trigonal (P3 1m) and the hexagonal (P63/mcm) polytypes of K2−xFe4O7 show oriented intergrowth. The sub-stoichiometric potassium content (x ≈ 0.3) is compensated by iron(IV), as supported by 57Fe Mößbauer spectroscopy, besides the dominating iron(III). K2−xFe4O7 is an antiferromagnet above 2 K and its magnetic structure was determined by neutron powder diffraction. Under ambient conditions, K2CO3·H2O forms gradually on the surface of K2−xFe4O7 crystals. Upon annealing at air at about 500 °C, the potassium atoms in the columnar halls start to order into a superstructure. The thermal de...

The superconductivity in highly compressed calcium involves the occurrence of closely related low-symmetry structural patterns with exceptionally low coordination number. Earlier theoretical and experimental results are controversial and some findings are inconsistent with our later observations in the pressure range up to GPa. This situation motivated the present concerted computational and experimental re-investigation of the structural arrangement of calcium slightly above the high-pressure limit of the bcc arrangement at low-temperatures. We report here reproducible experimental evidence for a monoclinic distortion (mC4, space group (C2/c) of the calcium polymorph previously assigned to the tetragonal β-Sn structure type. In accordance, the enthalpies calculated by electronic band structure calculations show the mC4 phase to be more stable than the undistorted β-Sn type by about 100 meV in the entire phase space. The other low-temperature phase of calcium adopts space group Cmcm (oC4) rather than the earlier assigned Cmmm symmetry. These structural alterations substantially effect the density of states at the Fermi level and, thus, the electronic properties.

Dedicated to Professor Arndt Simon on the Occasion of his 80th Birthday The oxohydroxoferrates(III) A 2 [Fe 2 O 3 (OH) 2 ] (A = K, Rb, Cs) were synthesized under hydroflux conditions. Approximately equimolar mixtures of the alkali metal hydroxides and water were reacted with Fe(NO 3) 3 • 9H 2 O at about 200°C. The product formation depends on the hydroxide concentration, therefore also other reaction products, such as KFeO 2 , K 2À x [Fe 4 O 7À x (OH) x ] or α-Fe 2 O 3 , are obtained. The crystal structures of the oxohydroxoferrates(III) A 2 [Fe 2 O 3 (OH) 2 ] follow the same structural principle, yet differ in their layer stacking or/and their hydrogen bonding systems depending on A and temperature. In the resulting four different orthorhombic structure types, [FeO 3 OH] 4À tetrahedra share their oxide corners to create folded 1 2 ½Fe 2 O 3 (OH) 2 ] 2À layers. The terminal hydroxide ligands form hydrogen bonds between and/or within the layers. The positions of the hydrogen atoms in these networks are correlated. The A + cations are located between the folded anionic layers as well as in their trenches. Under reaction conditions, the potassium compound crystallizes in the space group Cmce (Pearson symbol oC88), showing a bimodal disorder of the hydrogen atoms in hydrogen bridges. In a virtually hysteresis-less first-order transition at 340(2) K, the structure slightly distorts into the room-temperature modification with the subgroup Pbca (oP88), and the hydrogen atoms order. The rubidium and caesium compounds are isostructural to each other but not to the potassium compound, and are always obtained as mixtures of two modifications with space groups Cmce (oC88') and Immb (oI88). Upon heating, the oxohydroxoferrates decompose into their anhydrides AFeO 2 and water. The type of hydrogen bonding network influences the decomposition temperature, the structure and the morphology of the crystals. Despite the presence of iron(III), which was confirmed by 57 Fe-Mössbauer spectroscopy, K 2 [Fe 2 O 3 (OH) 2 ] is diamagnetic in the investigated temperature range between 1.8 and 300 K. Neutron diffraction revealed strong antiferromagnetic coupling of the magnetic moments, which are inverted in neighboring tetrahedra.