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  • 1
    Electronic Resource
    Electronic Resource
    A revision of the structure of (bipyridyl-N,N')-dicyanoplatinum(II) (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 817-822 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In a previous X-ray crystallographic study of crystals of Pt(bpy)(CN)2 (bpy = 2,2′-bipyridine) the planar molecules were reported to be exactly eclipsed, stacked directly on top of one another with a spacing of 3.33 Å so as to form a linear Pt...Pt...Pt chain. A reinvestigation shows this structure to be incorrect. The presence of weak intermediate layer lines indicates that the repeat distance along the stacking direction is 6.66 Å rather than 3.33 Å. Successive molecules within the stack are rotated by 180° and the resulting Pt-atom chain is slightly zigzag with a Pt...Pt...Pt angle of 168.6 (1)°. The implications are discussed of the determination and refinement of an apparently satisfactory, although grossly wrong, structure that was based on an incorrect unit cell and an incorrect space group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768196002674
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  • 2
    Electronic Resource
    Electronic Resource
    Some thoughts on choosing the correct space group (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 897-907 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768195008901
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  • 3
    Electronic Resource
    Electronic Resource
    A tribenzylidenemethane–tantalum compound: some experiences with `inversion twinning' (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 465-470 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The six-electron-donating ligand tribenzylidenemethandiide has been used to form a tantalum (group 5) mimic, (η5-cyclopentadienyl)(η4-tribenzylidenemethandiide)dimethyltantalum, of a group 4 bent metallocene. The material crystallizes with two molecules in the asymmetric unit with quite different packing arrangements, although the overall structures of the two are similar. The Cp and methyl ligands are disordered about a threefold axis. Crystal data: [Ta{(C7H6)3C}(C5H5)(CH3), trigonal P31c, with a = 12.681 (3), c = 16.124 (5) Å, V = 2245.5 (7) Å3, T = 293 K, Z = 4, Mr = 558.47, Dx = 1.65 g cm−3, F(000) = 1104, Mo Kα, λ = 0.71073 Å, μ = 4.91 mm−1, R = 0.020 for 1319 reflections with Fo 〉 4σ(Fo); S = 2.18. Because of crystal decay, three separate crystals were needed for a full data set. These polar (but achiral) crystals showed apparently differing amounts of inversion twinning, leading to problems in accurately merging the three data sets and refining the structure. These problems are discussed briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768195013255
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  • 4
    Electronic Resource
    Electronic Resource
    More Space-Group Corrections: From Triclinic to Centred Monoclinic and to Rhombohedral; Also From P1 to P-1 and From Cc to C2/c (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 677-686 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: We present 14 examples of crystal structures that were originally described as triclinic, but are properly described as either C-centred monoclinic (ten examples) or rhombohedral (four examples). There is also one example each of changes from P1 to P1¯ and from Cc to C2/c.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768198000949
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  • 5
    Electronic Resource
    Electronic Resource
    Arrays with Local Centers of Symmetry in Space Groups Pca21 and Pna21 (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 921-924 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Of the several hundred structures in the Cambridge Structural Database [version 4.6 (1992), Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, England] having space groups Pca21 or Pna21 and more than one molecule in the asymmetric unit (Z 〉 4), approximately three-quarters contain local centers of symmetry. These local centers, which are not crystallographic centers, occur predominantly near x = 1\over8, y = 1\over4 in Pca21 or near x = 1\over8, y = 0 in Pna21; this also holds for the limited number of examples we have examined of pseudo-centrosymmetric molecules with Z = 4. Local centers at these points create unusual correlations between corresponding atoms in the two molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768198007381
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  • 6
    Electronic Resource
    Electronic Resource
    A Revised Structure for Diethyl 5,11,17,23-Tetra-tert-butyl-26,28-bis(2-methoxyethoxy)calix[4]arene-25,27-bis(oxyacetate) (1995)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 157-158 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270194004506
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  • 7
    Electronic Resource
    Electronic Resource
    Concerning the κ Phase of Al–Cr–Ni (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 925-926 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of a new hexagonal phase aluminium–chromium–nickel, of reported composition Al14.4Cr3.4Ni1.1, has recently been described and refined in space group P63; most of the atom sites were described as disordered between various pairs of metal atoms [Sato et al. (1997). Acta Cryst. C53, 1531–1533]. A simpler structure, in space group P63/m, leads to better refinement. In the revised structure most of the atom sites are ordered. There is no indication of Ni in any of these ordered sites, but one partially occupied site may contain Ni, octahedrally coordinated to six Al atoms. Disordering along a chain of four atoms, parallel to the c axis, prevents a determination of the exact chemical composition; the approximate cell contents are Al177Cr49Ni.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768198007393
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  • 8
    Electronic Resource
    Electronic Resource
    The perils of Cc revisited (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 317-322 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The space groups of 98 structures originally reported in Cc are revised. In 75 cases the revised space group is C2/c and the revision entails adding a center of symmetry, usually leading to large changes in bond lengths and angles. In the remaining 23 cases, where the revised space group is Fdd2, R3c or (in one case) I\overline 4c2, the lattice type is changed but no center is added; in these cases the molecular dimensions are effectively unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876819601381X
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  • 9
    Electronic Resource
    Electronic Resource
    Is There Evidence for Non-Linear Thiocyanate or Selenocyanate Ions? (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 503-504 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of a mixed-valence copper complex with 1,10-phenanthroline, [CuII(phen)2]–NC–[CuI(phen)((Se,S)CN)]- [(Se,S)CN].0.5(C2H5OH), μ-cyano-1κN:2κC-(seleno,thio)cyanato-2κN-tris(1,10-phenanthroline)-1κ4N,N′;2κ2N,N′-dicopper(I,II) (seleno,thio)cyanate semiethanolate, has been revised from space group Cc to C2/c. Refinement in C2/c has shown that, contrary to the Cc results, the (Se,S)CN anions can be described as approximately linear, as expected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768198003401
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  • 10
    Electronic Resource
    Electronic Resource
    More space-group changes (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 300-307 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768194011857
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