Kristallstrukturanalyse von (NH4)2NaInF6

Single Crystal Structure of (NH₄)₂NaInF₆ (NH₄)₂NaInF₆ has been synthesized via a novel route from In₂O₃, NaF and NH₄F and its crystal structure has been determined using single crystal techniques (Fm3 m, a = 8.6675(3) Å, Z = 4, 4 106 reflections, R = 0.007). The crystal structure derives from the elpasolite type of structure, the ammonium ions are not disordered.     

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°.     

Röntgenstrukturanalytische Untersuchungen von Diazadiphosphetidinen

X‐Ray Structure Analysis of Diazadiphosphetidines Various diazadiphosphetidines are synthesized by a modified Kirsanov reaction and subjected to X‐ray crystal structure analysis, the results of which show steric hindrance in the cyclohexyl‐substituted compound 4 . A comparison of its structure to that of the fluorine compound 12 shows that the steric hindrance occurs only in the case of chlorophosphoranes. During the Kirsanov reaction with aliphatic amines branched at the α‐position, a further reaction is observed if the amine is added in excess. The phosphonium salt 11 is characterized by ¹H‐, ¹³C‐ and ³¹P‐NMR‐spectra, FAB‐mass spectrum, elemental analysis and X‐ray crystal structure analysis.     

DSC Monitoring of the Spin Crossover in Fe(II) Complexes

Heat flow to [Fe(bzimpy)²](ClO₄)₂⋅0.25H₂O complex (bzimpy=2,6-bis(benzimidazol-2-yl)pyridine) (I) was measured between 300 and 460 K by differential scanning calorimetry. This exhibits a well-developed peak characteristic of the first-order phase transitions at temperature 403 K. The enthalpy and entropy of transition from low-spin to high-spin state has been determined to be ΔH=17 kJ mol⁻¹ and ΔS=43.0 Jmol⁻¹ K⁻¹. Heat flow to [Fe(bzimpy_−1H)₂]⋅H₂O complex (bzimpy _−1H=deprotonated bzimpy) (II) was measured between 300 and 580 K. The spin crossover in this system is accompanied with liberation of crystal water on the first heating. To monitor the structural changes during the spin crossover, powder diffraction data have been collected as a function of temperature. This revised version was published online in August 2006 with corrections to the Cover Date.     

β-SrNH und β-SrND – Synthese und Kristallstrukturbestimmung mittels Röntgen- und Neutronenbeugung an Pulvern

β-SrNH and β-SrND – Synthesis and Crystal Structure Determination by X-Ray and Neutron Powder Diffraction By reaction of strontium with NH₃ in a flow tube at 750 °C a novel modification of strontium imide, β-SrNH, was obtained as a dark yellow powder. According to X-ray powder diffractometry und crystal structure determination by direct methods β-SrNH and β-SrND adopt a highly distorted variant of the NaCl type of structure (Pnma, a = 757.70(1), b = 392.260(4), c = 569.652(9) pm, Z = 4, wR_p = 0.098, R_p = 0.075, R_F = 0.044). Temperature dependent neutron powder diffraction of β-SrND revealed the position of the D atoms which in contrast to α-SrND are crystallographically ordered. At higher temperatures β-SrNH transforms to α-SrNH.     

Röntgenographische Untersuchungen und Strukturchemie von Chalkogenomolybdaten und -wolframaten. II

X-Ray Investigations and Structure Chemistry of Chalkogenomolybdates and -tungstates. II. The chalkogenomolybdates and -tungstates (NH₄)₂MoS₃Se, (NH₄)₂MoS₂Se₂, (NH₄)₂MoSSe₃, (NH₄)₂WSSe₃, Cs₂MoS₂Se, Cs₂MoS₂Se, Cs₂MoSSe₃, Cs₂WSSe₃, Cs₂MoOS₂Se, Cs₂WOS₂Se, Cs₂MoOSSe₂, and Cs₂WOSSe₂ are investigated by means of X-ray powder diffractometry. All compounds crystallize orthorhombic in spacegroup D? Pnma and are isomorphous with β-K₂SO₄. Systematic relations between lattice constants and occupation of atomic positions in the unit cell are discussed.     

Structures and crystal chemistry of the double perovskites Ba2LnB′O6 (Ln=lanthanide B′=Nb and Ta): Part I. Investigation of Ba2LnTaO6 using synchrotron X-ray and neutron powder diffraction

The structure of 14 compounds in the series Ba₂LnTaO₆ have been examined using synchrotron X-ray diffraction and found to undergo a sequence of phase transitions from I2/m monoclinic to I4/m tetragonal to cubic symmetry with decreasing ionic radii of the lanthanides. Ba₂LaTaO₆ is an exception to this with variable temperature neutron diffraction being used to establish that the full series of phases adopted over the range of 15-500 K is P2₁/n monoclinic to I2/m monoclinic to rhombohedral. The chemical environments of these compounds have also been investigated and the overbonding to the lanthanide cations is due to the unusually large size for the B-site in these perovskites.     

Tieftemperaturuntersuchung von Wasserstoffbrückenbindungen in Lithiumtetrahydroxoborat mit Raman‐Spektroskopie,Röntgen‐ und Neutronenbeugung (Li11B(OD)4)

Low Temperature Investigation of Hydrogen Bridge Bonds in Lithium Tetrahydroxoborate by Raman Spectroscopy, X‐Ray and Neutron Diffraction (Li¹¹B(OD)₄) Low temperature Raman spectroscopic measurements on isotopically diluted Li¹¹B(OH)₄ with 8 % D and Li¹¹B(OD)₄ with 8 % H reveal four crystallographically different hydrogen bridge bonds. With decreasing temperatures beginning at ～50 K measured down to ～10 K the stretching modes of the hydroxide ions shift to higher wave numbers. For the strongest bond O–D···O the frequency shift is 16 cm^?1and for the weakest 7 cm^?1. For O–H···O the maximum in the frequency shift is 22 cm^?1. X‐ray single crystal (LiB(OH)₄) and neutron powder diffraction (Li¹¹B(OD)₄) data result in bond lengths for the four hydroxide ions in the range of 0.943 (3) Å ≤ d(O–D) ≤ 0.974 (3) Å. The value of the effect of inversion of the stretching mode frequencies seems to correlate with the strength of the hydrogen bridge bonds and is found to be different for the two isotopes H and D in this compound.     

Structures and crystal chemistry of the double perovskites Ba2LnB′O6 (Ln=lanthanide and B′=Nb, Ta):: Part II—Temperature dependence of the structures of Ba2LnB′O6

The structures of eight members of the series of double perovskites of the type Ba₂LnB′O₆ (Ln=La³⁺-Sm³⁺ and Y³⁺ and B′=Nb⁵⁺ and Ta⁵⁺) were examined both above and below room temperature using synchrotron X-ray powder diffraction. The La³⁺ and Pr³⁺ containing compounds had an intermediate rhombohedral phase whereas the other tantalates and niobates studied have a tetragonal intermediate. This difference in symmetry appears to be a consequence of the larger size of the La³⁺ and Pr³⁺ cations compared to the other lanthanides. The temperature range over which the intermediate symmetry is stable is reduced in those compounds near the point where the preferred intermediate symmetry changes from tetragonal to rhombohedral. In such compounds the transition to the cubic phase involves higher order terms in the Landau expression. This suggests that in this region the stability of the two intermediate phases is similar.