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  • 1
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of the crown ether 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol, C24H30O6·H2O (1), code name P326, the parent compound for a series of derivatives, has been determined by both X-ray diffraction at room temperature and neutron diffraction at very low temperature. The unit cells are very similar at both temperatures and in both cases the crystals exhibit P21 symmetry with Z = 4 (two molecules, A and B, respectively, per asymmetric unit) and pseudosymmetry P21/c. The higher symmetry is broken mainly by the two independent water molecules in the unit cell, some reflections which would be absent in P21/c having strong intensities in both the X-ray and neutron data. In both molecules A and B hydrogen bonds involving the water molecule stabilize the macrocyclic ring structure, one involving the macrocyclic O(9) as a donor. Close contacts between the water and macrocyclic O atoms in each molecule also suggest the presence of two bifurcated hydrogen bonds, involving water HW2 to both O(16) and O(18), and water HW1 to both O(18) and O(20), respectively, with considerable variation in the geometry being present. Both molecules A and B exhibit very close pseudosymmetry across a plane perpendicular to the molecular plane and through atoms C(9) and O(18), and in addition are predominantly planar structures. The X-ray analysis failed to reveal one H atom per water molecule, each being subsequently included after location and refinement in the neutron analysis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 3924-3935 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Complexes of Cyclic π-Ligands, VII1)Crystal and Molecular Structure of Tricarbonyl(1,4-dimethyl-1,2-dihydropyridine)chromium(0)The crystal and molecular structure of tricarbonyl(1,4-dimethyl-1,2-dihydropyridine)chromium(0) (1) has been determined by three-dimensional single crystal X-ray diffraction analysis. The compound crystallizes in the monoclinic system, a == 7.45 ± 0·01, b == 14.41 ± 0·02, c == 11.53 ± 0·02 Å, ß == 118.92 ± 0·08°, space group P21/c, Z ==4. The structure has been refined in an anisotropic model, all hydrogen atoms have been located by difference Fourier methods. The agreement factor for the 1315 independent nonzero observations is R == 0·0498. The molecule consists of a Cr(CO)3-fragment which is bonded to 5 atoms of the 1,4-dimethyl-1,2-dihydropyridine ligand. The ligand atoms which are bonded to the metal are coplanar to within 0·05 Å, the methylene group is bent out of this plane by 44.7° in the direction opposite to the metal atom. The chromium atom lies 1·70 Å below this plane. The Cr-N-distance is 2.116 ± 0·004 Å, the mean Cr-CLigand-distance is 2.21 Å, the Cr-CCO-distances average at 1·842 Å.
    Notes: Die Kristall- und Molekülstruktur von Tricarbonyl(1,4-dimethyl-1,2-dihydropyridin)chrom(0) (1) wurde durch eine dreidimensionale Einkristall-Röntgenbeugungsanalyse aufgeklärt. Die Verbindung kristallisiert im monoklinen System, a == 7.45 ± 0·01, b == 14.41 ± 0·02, c == 11.53 ± 0·02 Å, ß == 118.92 ± 0·08°, Raumgruppe P21/c, Z ==4. Die Struktur wurde vollständig anisotrop verfeinert, alle Wasserstoffatome wurden mit Differenz-Fourier-Methoden gefunden. Der Übereinstimmungsfaktor beträgt für die 1315 unabhängigen, von Null verschiedenen Beobachtungen R == 0·0498. Das Molekül besteht aus einem Cr(CO)3-Rest, der an 5 Atome des 1,4-Dimethyl-1,2-dihydropyridin-Liganden gebunden ist. Die an das Metall gebundenen Ligandenatome liegen innerhalb 0·05 Å in einer Ebene, die Methylen gruppe ist 44.7° aus dieser Ebene abgewinkelt und weist auf die dem Metallatom abgewandte Seite des Rings. Das Chromatom liegt 1·70 Å unter der Ebene, der Cr-N-Abstand beträgt 2.116 ± 0·004 Å, der mittlere Cr-CLigand-Abstand ist 2.21 Å, die Cr-CCO-Abstände betragen im Mittel 1·842 Å.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 301-311 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Complexes of Cyclic π-Ligands, III. Crystal and Molecular Structure of Tricarbonyl(N-methylpyrrole)chromium(0)Tricarbonyl(N-methylpyrrole)chromium(0) (1) crystallizes in space group P 21/c with a = 7.797 ± 0.008, b = 11.31 ± 0.01, c = 11.90 ± 0.01 Å, β = 124.96 ± 0.08°, Z = 4. The structure of the compo9und has been solved by three-dimensional single crystal X-ray diffraction analysis (R = 0.0529 for 1501 independent nonzero observations). The structure of the molecule is typically that of a tricarbonyl(arene)metal-complex. The three Cr-CCO-bonds are approximately mutually orthogonal. On the side opposite to the carbonyl groups the pyrrole ligand is bonded to the metal with the ring plane nearly parallel to the plane formed by the carbon atoms of the carbonyl groups. The five atoms of the ring are coplanar to within 0.006 Å. In contrast ot the planar free N-methylpyrrole the methyl group is bent out of the ring plane by 8.9° in the direction opposite to the chromium atom in the complex. The bond distances in the ligand are not significantly longer than in uncomplexed pyrrole. This may be taken as indicative of an only weak interaction between the ligand and the metal atom.
    Notes: Tricarbonyl(N-methyl-pyrrol)chrom(0) (1) kristallisiert in der Raumgruppe P 21/c mit a = 7.797 ± 0.008, b = 11.31 ± 0.01, c = 11.90 ± 0.01 Å, β = 124.96 ± 0.08°, Z = 4. Die Struktur der Verbindung wurde mit Hilfe einer dreidimensionalen Einkristall-Röntgenbeugungsanalyse gelöst (R = 0.0529 für 1501 unabhängige, von Null verschiedene Meßwerte). Das Molekül besitzt den für Tricarbonyl(aromat)metall-Komplexe typischen Bau. Die drei Cr-CCO-Bindungen bilden nahezu rechte Winkel miteinander. Annähernd parallel zu der durch die Kohlenstoffatome der Carbonylgruppen gebildeten Ebene liegt auf der anderen Seite des Chromatoms der Pyrrolring. Die fünf Atome des Rings liegen innerhalb von 0.006 Å in einer Ebene. Anders als im freien N-Methyl-pyrrol, das eben gebaut ist, ist im Komplexe die Methylgruppe um 8.9° aus der Ringebene heraus vom Chrom weg abgewinkelt. Die Bindungsabstände im Ring sind gegenüber den Abständen im unkomplexierten Pyrrol nicht signifikant aufgeweitet. Dies spricht für eine nur schwache Wechselwirkung zwischen dem Liganden und dem Metallatom.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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