Filters

1999 - 199942000 - 200826

More filters

2019 - 202030
Reset filters

Settings

End date: 2008 × Subject: Crystal structure ×

Search Results

Now showing 1 - 10 of 30
  • Thumbnail Image
    Item
    (μ5-Cyclo-penta-dien-yl)bis-(triphenyl-phosphane)cobalt(I) -toluene-n-hexane (1/0.20/0.25)
    (Chester : International Union of Crystallography, 2008) Hapke, M.; Spannenberg, A.
    The title compound, [Co(C5H5)(C18H15P)2]·0.2C7H8·0.25C6H14, was synthesized by the reaction of cobaltocene, Cp2Co, with elemental lithium in tetra-hydro-furan in the presence of two equivalents of PPh3. The mol-ecular structure displays a cobalt(I) center in a distorted trigonal-planar coordination environment, with one Cp and two phosphane ligands. There are two crystallographically independent mol-ecules in the asymmetric unit besides the disordered solvent molecules.
  • Thumbnail Image
    Item
    Redetermination of terbium scandate, revealing a defect-type perovskite derivative
    (Chester : International Union of Crystallography, 2008) Veličkov, B.; Kahlenberg, V.; Bertram, R.; Uecker, R.
    The crystal structure of terbium(III) scandate(III), with ideal formula TbScO3, has been reported previously on the basis of powder diffraction data [Liferovich & Mitchell (2004). J. Solid State Chem. 177, 2188-2197]. The current data were obtained from single crystals grown by the Czochralski method and show an improvement in the precision of the geometric parameters. Moreover, inductively coupled plasma optical emission spectrometry studies resulted in a nonstoichiometric composition of the title compound. Site-occupancy refinements based on diffraction data support the idea of a Tb deficiency on the A site (inducing O defects on the O2 position). The crystallochemical formula of the investigated sample thus may be written as A(0.04Tb0.96) BScO2.94. In the title compound, Tb occupies the eightfold- coordinated sites (site symmetry m) and Sc the centres of corner-sharing [ScO6] octa-hedra (site symmetry ). The mean bond lengths and site distortions fit well into the data of the remaining lanthanoid scandates in the series from DyScO3 to NdScO3. A linear structural evolution with the size of the lanthanoid from DyScO3 to NdScO3 can be predicted.
  • Thumbnail Image
    Item
    Optical study of orbital excitations in transition-metal oxides
    (Milton Park : Taylor & Francis, 2005) Rückamp, R.; Benckiser, E.; Haverkort, M.W.; Roth, H.; Lorenz, T.; Freimuth, A.; Jongen, L.; Möller, A.; Meyer, G.; Reutler, P.; Büchner, B.; Revcolevschi, A.; Cheong, S.-W.; Sekar, C.; Krabbes, G.; Grüninger, M.
    The orbital excitations of a series of transition-metal compounds are studied by means of optical spectroscopy. Our aim was to identify signatures of collective orbital excitations by comparison with experimental and theoretical results for predominantly local crystal-field excitations. To this end, we have studied TiOCl, RTiO3 (R = La, Sm and Y), LaMnO3, Y2BaNiO5, CaCu2O3 and K4Cu4OCl10, ranging from early to late transition-metal ions, from t2g to eg systems, and including systems in which the exchange coupling is predominantly three-dimensional, one-dimensional or zero-dimensional. With the exception of LaMnO3, we find orbital excitations in all compounds. We discuss the competition between orbital fluctuations (for dominant exchange coupling) and crystal-field splitting (for dominant coupling to the lattice). Comparison of our experimental results with configuration-interaction cluster calculations in general yields good agreement, demonstrating that the coupling to the lattice is important for a quantitative description of the orbital excitations in these compounds. However, detailed theoretical predictions for the contribution of collective orbital modes to the optical conductivity (e.g. the line shape or the polarization dependence) are required to decide on a possible contribution of orbital fluctuations at low energies, in particular, in case of the orbital excitations at ≈0.25 eV in RTiO3. Further calculations are called for which take into account the exchange interactions between the orbitals and the coupling to the lattice on an equal footing.
  • Thumbnail Image
    Item
    Crystal structure of praseodym gallate, Pr4Ga2O9
    (München : R. Oldenbourg Verlag GmbH, 1999) Gesing, T.M.; Uecker, R.; Buhl, J.-C.
    Ga2O9Pr4, monoclinic, P121/c1 (No. 14), a = 7.8256(4) Å, b = 11.0322(5) Å, c = 11.4959(7) Å, β = 109.187(3)°, V = 937.4 Å3, Z = 4, R(P) = 0.026, wR(P) = 0.034, R(I)= 0.033, T = 295 K.
  • Thumbnail Image
    Item
    Crystal structure of bis(1,3-bis[{4-methyl-pyridin-2-yl}amido]-1,1,3,3-tetramethyldisiloxane)dichromium dichloride, [(C16H24N4OSi2)CrCl]2
    (Berlin : de Gruyter, 2006) Irrgang, T.; Spannenberg, A.; Kempe, R.
    C32H48Cl2Cr2N8O2Si=, monoclinic, P121/n1 (no. 14), a = 12.416(2) Å, b = 13.668(3) Å, c = 13.172(3) Å, β = 113.83(3)°, V= 2044.8 A3, Z = 2, Rgt(F) = 0.052, wRref(F2) = 0.110, T = 200 K. © 2014 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München. All rights reserved.
  • Thumbnail Image
    Item
    Crystal structure of μ-oxo-bis(σ- 1,2-bis(trimethylsilyl) vinylhafnocene) benzene solvate, [C2H{Si(CH3) 3}2Hf(C5H5)2] 2O ·C6H6
    (Berlin : de Gruyter, 2007) Spannenberg, A.; Beweries, T.; Bach, M.A.; Rosenthal, U.
    C42H64Hf2OSi4, monoclinic, P121/c1 (no. 14), a = 11.442(1) Å = 9.7998(6) Å, c = 19.827(2) Å, β = 95.229(7)°, V = 2213.9 Å, Z = 2, R gt(F) = 0.017, wRref(F2)=0.037, T=200K. © by Oldenbourg Wissenschaftsverlag,.
  • Thumbnail Image
    Item
    Crystal structure of (η4-cycloocta-1,5-dien)-N-(2- (diphenylphosphinooxy)-3-(naphthalen-1-yloxy)propyl)-N-(pentan-3-yl)-1, 1-diphenylphosphinamine-rhodium(I) tetrafluoroborate, [Rh(C8H 12)(C42H43NO2P2)][BF 4]
    (Berlin : de Gruyter, 2007) Dai, Z.; Heller, D.; Preetz, A.; Drexler, H.-J.
    C50H55BF4NO2P2Rh, monoclinic, P1211 (no. 4), a = 12.722(3) Å, b = 15.248(3) Å, c = 12.818(3) Å, β = 115.80(3)°, V = 2238.7 Å3, Z = 2, Rgt(F) = 0.036, wRref(F 2) = 0.079, T = 200 K. © by Oldenbourg Wissenschaftsverlag.
  • Thumbnail Image
    Item
    Crystal structure of (η4-cycloocta-1,5-dien)(1,2-bis(diethylphosphino)-ethane)rhodium(I) tetrafluoroborate, [Rh(C8H12(C10H24P2)]BF4)
    (München : R. Oldenbourg Verlag GmbH, 2004) Kempe, R.; Spannenberg, A..; Heller, D.; Drexler, H.-J.
    C18H36BF4P2RI1, monoclinic, P121/n1 (no. 14), a = 15.522(3) Å, b = 9.173(2) Å, c = 15.862(3) Å, β = 103.91(3)°, V= 2192.3 Å3, Z = 4, Rgt(F) = 0.037, wRref(F2) = 0.087, T=200 K.
  • Thumbnail Image
    Item
    Crystal structures of tribromo(η5-3,6-di-tert-butyl-9,10,11- trimethyl-bicyclo(6.3.0)undeca-4-en-8,10-dienyl)titanium(IV), Ti(C 22H35)Br3, and tribromo(η5-4,5- dibromo-3,6-di-tert-butyl-9,10,11-trimethyl-bicyclo(6.3.0)undeca-8,10-dienyl) titanium(IV), Ti(C22H35Br2)Br3
    (Berlin : de Gruyter, 2008) Spannenberg, A.; Burlakov, V.V.; Rosenthal, U.
    C22H35Br3Ti, triclinic, P1̄ (no. 2), a = 9.621(2) Å, b = 11.796(2) Å, c = 12.232(2) Å, α = 102.23(3)°, β = 97.71(3)°, γ = 112.32(3)°, V = 1219.2 Å3, Z = 2, Rgt(F) = 0.058, wRobs(F 2) = 0.134, T = 293 K. C22H35Br5Ti, monoclinic, P121/n1 (no. 14), a = 7.474(1) Å, b = 18.458(4) Å, c = 20.171(4) Å, β = 100.28(3)°, V= 2738.0 Å3, Z = 4, Rgt(F) = 0.054, wRobs(F 2) = 0.119, T = 293 K. © by Oldenbourg Wissenchaftsverlag.
  • Thumbnail Image
    Item
    Crystal structure of η5-3,6-di-tert-butyl-4- (tris(pentafluorophenyl)boranyloxycarbonyl)-5-(η5- tetramethylcyclopentadienyl-methyl-9,10,11-trimethyl-bicyclo(6.3.0) undeca-4-en-8,10-dienyl)titanium(III) toluene hemisolvate, Ti(C 51H47BF15O2) · 0.5C 7H8
    (Berlin : de Gruyter, 2008) Spannenberg, A.; Burlakov, V.V.; Rosenthal, U.
    C54.50H51BF15O2Ti, triclinic, P1̄ (no. 2), a = 11.603(2) Å, b = 12.872(3) Å, c = 18.142(4) Å, α = 76.47(3)°, β = 77.99(3)°, γ = 69.13(3)°, V = 2438.2 Å5, Z = 2, Rgt(F) = 0.048, wRobs(F2) = 0.114, T = 200 K. © by Oldenbourg Wissenchaftsverlag.