Jürgen Senker

High-Pressure Synthesis ofγ-P3N5 at 11 GPa and 1500 °C in a Multianvil Assembly: A Binary Phosphorus(V) Nitride with a Three-Dimensional Network Structure from PN4 Tetrahedra and Tetragonal PN5 Pyramids

Extreme reaction conditions lead to the synthesis of γ-P3 N5 . Its crystal structure, unlike that of the normal pressure modification α-P3 N5 , is not exclusively built from PN4 tetrahedra, but from both PN4 tetrahedra (blue) and tetragonal PN5 pyramids (red). A tetragonal PN5 pyramid structure element has not been observed previously.

Multianvil-Synthese, Pulver-Röntgenstrukturanalyse, 31P-MAS-NMR- und FTIR-Spektroskopie sowie Materialeigenschaften von γ-P3N5, einer Hochdruckphase von binärem Phosphor(V)-nitrid mit verzerrt quadratischen PN5-Pyramiden und PN4-Tetraedern†

Die Hochdruckphase γ-P3N5 wurde ausgehend von teilkristallinem P3N5 bei einem Druck von 11 GPa und einer Temperatur von 1500 °C in einer Multianvil-Apparatur synthetisiert. Die Kristallstruktur wurde auf der Basis von Pulver-Rontgenbeugungsdaten mit Direkten Methoden gelost und nach dem Rietveld-Verfahren verfeinert (Imm2, a = 1287, 21(4), b = 261, 312(6), c = 440, 03(2) pm, Z = 2, Rp = 0, 073, wRp = 0, 094, RF = 0, 048). γ-Phosphor(V)-nitrid kristallisiert demnach in einer Raumnetzstruktur aus eckenverknupften PN4-Tetraedern und verzerrt quadratischen PN5-Pyramiden. In Ubereinstimmung mit der Rontgenstrukturanalyse werden im 31P-MAS-NMR-Spektrum von γ-P3N5 zwei scharfe isotrope Resonanzen bei —11, 95(3) und —101, 72(7) ppm im Intensitatsverhaltnis 1 : 2, 02(5) gefunden. Die IR-spektroskopischen Eigenschaften sowie das thermische Verhalten von γ-P3N5 werden beschrieben. Messungen der Vickers-Harte ergaben fur gesinterte Presslinge aus polykristallinem γ-P3N5 einen Wert von 9, 7(21) GPa. Dieser liegt deutlich uber dem fur teilkristallines P3N5 (5, 1(7) GPa). n n n nMultianvil Synthesis, X-ray Powder Diffraction Analysis, 31P-MAS-NMR, and FTIR Spektroscopy as well as Material Properties of γ-P3N5, a High-Pressure Polymorph of Binary Phosphorus(V) Nitride, Built up from Distorted PN5 Square Pyramids and PN4 Tetrahedra n n n nThe high-pressure phase γ-P3N5 was synthesized at a pressure of 11 GPa and a temperature of 1500 °C in a multianvil apparatus. Partially crystalline P3N5 has been used as a starting material. The crystal structure was solved by direct methods on the basis of X-ray powder diffraction data and it was refined by the Rietveld method (Imm2, a = 1287.21(4), b = 261.312(6), c = 440.03(2) pm, Z = 2, Rp = 0.073, wRp = 0.094, RF = 0.048). γ-phosphorus nitride crystallizes in a three-dimensional network structure built up from corner sharing PN4 tetrahedra and trans-edge sharing distorted PN5 square pyramids. In the 31P-MAS-NMR spectrum two sharp isotropic resonances with an intensity ratio of 1 : 2.02(5) are observed at —11.95(3) and —101.72(7) ppm, respectively. The IR-spectroscopic and thermal properties of γ-P3N5 are described. Measurement of the Vickers hardness resulted in a value of 9.7(21) GPa for sintered polycrystalline γ-P3N5, which is significantly higher than that for the partially crystalline normal pressure modification of P3N5 (5.1(7) GPa).

Investigation of structural and dynamic properties of NH4[N(CN)2] by means of X-ray and neutron powder diffraction as well as vibrational and solid-state NMR spectroscopy

Abstract The crystal structure, spectroscopic and thermal properties of ammonium dicyanamide NH4[N(CN)2] have been thoroughly investigated by means of temperature-dependent single-crystal X-ray and neutron powder diffraction, vibrational and MAS-NMR spectroscopy as well as thermoanalytical measurements. The comprehensive elucidation of structural details is of special interest with respect to the unique solid-state transformation of ammonium dicyanamide into dicyandiamide. This reaction occurs at temperatures >80°C and it represents the isolobal analogue of Wohlers historic transformation of ammonium cyanate into urea. NH4[N(CN)2] crystallizes in the monoclinic space group P21/c with lattice constants a=3.7913(8), b=12.412(2), c=9.113(2)xa0A, β=91.49(2)° and Z=4 (single-crystal X-ray data, T=200xa0K). The temperature dependence of the lattice constants shows anisotropic behavior, however, no evidence for phase transitions in the investigated temperature range was observed. The hydrogen positions could be localized by neutron diffraction (10–370xa0K), and the temperature-dependent behavior of the ammonium group has been analyzed by Rietveld refinements using anisotropic thermal displacement parameters. They were interpreted by utilizing a rigid body model and extracting the libration and translation matrices of the ammonium ion by applying the TLS formalism. The results obtained by the diffraction methods were confirmed and supplemented by vibrational spectroscopy and solid-state 15N and 13C MAS-NMR investigations.

Pure silica BETA colloidal zeolite assembled in thin films

Pure silica nanoscale zeolite BETA with monomodal particle size distribution was synthesized from a colloidal precursor solution and successfully applied for the preparation of hydrophobic ultrathin films on silicon wafers via spin coating.

High-temperature synthesis, single-crystal X-ray structure determination and solid-state NMR investigations of Ba7[SiO4][BO3]3CN and Sr7[SiO4][BO3]3CN

Abstract The novel alkaline earth silicate borate cyanides Ba 7 [SiO 4 ][BO 3 ] 3 CN and Sr 7 [SiO 4 ][BO 3 ] 3 CN have been obtained by the reaction of the respective alkaline earth metals M =Sr, Ba, the carbonates M II CO 3 , BN, and SiO 2 using a radiofrequency furnace at a maximum reaction temperature of 1350°C and 1450°C, respectively. The crystal structures of the isotypic compounds M II 7 [SiO 4 ][BO 3 ] 3 CN have been determined by single-crystal X-ray crystallography ( P 6 3 mc (no. 186), Z =2, a =1129.9(1) pm, c =733.4(2)xa0pm, R 1 =0.0336, w R 2 =0.0743 for M II =Ba and a =1081.3(1)xa0pm, c =695.2(1)xa0pm, R 1 =0.0457, w R 2 =0.0838 for M II =Sr). Both ionic compounds represent a new structure type, and they are the first examples of silicate borate cyanides. The cyanide ions are disordered and they are surrounded by Ba 2+ /Sr 2+ octahedra, respectively. These octahedra share common faces building chains along [001]. The [BO 3 ] 3− ions are arranged around these chains. The [SiO 4 ] 4− units are surrounded by Ba 2+ /Sr 2+ tetrahedra, respectively. The title compounds additionally have been investigated by 11 B, 13 C, 29 Si, and 1 H MAS-NMR as well as IR and Raman spectroscopy confirming the presence of [SiO 4 ] 4− , [BO 3 ] 3− , and CN − ions.

Structure Determination for the Crystalline Phase of Triphenyl Phosphite by Means of Multi-Dimensional Solid-State NMR and X-Ray Diffraction

The crystalline phase of triphenyl phosphite P(OC6H5)3 was investigated by means of 31P solid-state NMR and X-ray diffraction in a temperature range between 170 K and its melting point (Tm = 293 K). ID MAS NMR spectra exhibit one sharp central resonance indicating only one crystallographically unique molecule in the unit cell. A theoretical analysis concerning the shape of 2D exchange spectra for 1 = 1 /2 nuclei is presented. It is shown that if the exchange is caused by radio-frequency driven spin-diffusion, this technique allows to discriminate rotational symmetry elements in crystalline solids. Used on crystalline triphenyl phosphite, 3-fold symmetry could be revealed clearly. Structure determination based on X-ray single crystal diffraction data collected at 191 K shows that triphenyl phosphite crystallises in hexagonal metric with space group R3̅(wR2= 8.3%, Z = 18) and one molecule in the asymmetric unit. This result is in excellent agreement with the NMR spectroscopic data. The lattice parameters at 200 K were determined to a = 37.887(1) and c = 5.7567(2) Å (V = 7156(1) Å3) by refining an X- ray powder-diffraction pattern. The structure of triphenylphosphite can be described as a close rod packing. The rods are formed by ecliptically arranged triphenylphosphite molecules. Due to the 3-fold rotoinversion axis the orientation of molecules in neighboured rods is antiparallel.

Characterisation of the tetrahalophosphonium cations PBrnI4 − n+ (0 ≤ n ≤ 4) by 31P MAS NMR, IR and Raman spectroscopy and the crystal structures of PI4+AlCl4−, PI4+AlBr4− and PI4+GaI4−

The novel tetrahalophosphonium salts PBr4+AsF6−, PI4+AlCl4− and PI4+EBr4− (Exa0=xa0Al, Ga) have been synthesised. A variety of solid complexes containing PBr4+ (e.g. PBr4+AsF6−, PBr4+AlBr4− PBr4+GaBr4−), PI4+ (e.g. PI4+AlCl4−, PI4+AlBr4−, PI4+GaBr4−) or the mixed species PBrnI4xa0−xa0n+ (0xa0≤xa0nxa0≤xa04, containing AlBr4−, GaBr4−, AsF6− or SbF6−) have been studied by solid-state 31P MAS NMR and vibrational spectroscopy. The influence of the counter-ion on the chemical shift and the vibrational frequencies are discussed. The crystal structures of PI4+AlCl4−, PI4+AlBr4− and PI4+GaI4− are reported. Evidence for the existence of the hitherto unknown mixed bromoiodophosphonium cations PBr3I+, PBr2I2+ and PBrI3+ has been confirmed by spin–orbit corrected density functional calculations of isotropic 31P chemical shifts for PBrnI4xa0−xa0n+.

Polyol-Metall-Komplexe, 43 [1]. Galactarato-Komplexe mit Aluminium und Kupfer(II) / Polyol Metal Complexes, 43 [1]. Galactarato Complexes with Aluminium and Copper(II)

Na6[Al6(Gal1,6A21,2,5,6H−4)4(OH)8] ∙ 21 H2O (1) crystallizes from alkaline aqueous solutions of galactaric acid (Gal1,6A2) and aluminium nitrate. Crystal structure analysis (P1̄, a = 9.09950(10), b = 15.1996(2), c = 21.9667(3) Å , α = 96.6190(5), β = 90.5307(4), γ = 103.5658(5)°, V = 2931.66(6) Å3, Z = 2) and solid state 27Al NMR spectroscopy reveal rings of six edge-sharing AlO6 octahedra, the O-atoms stemming from four galactarato and eight hydroxo ligands. The potassium homologue K6[Al6(Gal1,6A21,2,5,6H−4)4(OH)8] ∙ 23 H2O (2) is not isotypic (P21/c, a = 9.7604(6), b = 22.0843(17), c = 30.1534(17) Å , β = 95.970(7)°, V = 6464.4(7) Å3, Z = 4), but the anion structure is the same. Pure polyolato coordination of entirely deprotonated galactarate has been found in Na4[Cu(Gal1,6A2H−6)]] ∙ 12 H2O (3). In 3, a coordination polymer is formed by the copper atoms and the erythro-bis-diolate ligand (P1̄, a = 5.9711(2), b = 9.5319(3), c = 9.7794(3) Å , α = 99.883(2), β = 100.807(2), γ = 105.9182(11)°, V = 510.90(3) Å3, Z = 1).