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Disordered Molecules (disordered + molecule)

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Chemistry100%

Selected Abstracts

The 293,K structure of tetradehydrohaliclonacyclamine A

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010
I. Wayan Mudianta
The polycyclic title compound {systematic name: (1S,16S,17S,31S)-3,20-diazatetracyclo[15.15.01,17.13,31.116,20]tetratriaconta-6,8,23,25-tetraene}, C32H52N2, has recently been isolated and characterized structurally, in solution by NMR spectroscopy and in the solid state by X-ray crystallography. At 130,K the structure is monoclinic (P21, Z = 4) and comprises two molecules in the asymmetric unit with distinctly different conformations in the twelve-C-atom bridging chains. We report that, at 250,K, a phase change from monoclinic to orthorhombic (P22121, Z = 4) occurs. The higher-temperature phase is structurally characterized herein at 293,K. The two different conformers resolved in the monoclinic low-temperature form merge to give a single disordered molecule in the asymmetric unit of the high-temperature phase. [source]

Structural effects on the solid-state photodimerization of 2-pyridone derivatives in inclusion compounds

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009
Marina Telzhensky
The structures of six crystalline inclusion compounds between various host molecules and three guest molecules based on the 2-pyridone skeleton are described. The six compounds are 1,1,-biphenyl-2,2,-dicarboxylic acid,2-pyridone (1/2), C14H10O4·2C5H5NO, (I,a), 1,1,-biphenyl-2,2,-dicarboxylic acid,4-methyl-2-pyridone (1/2), C14H10O4·2C6H7NO, (I,c), 1,1,-biphenyl-2,2,-dicarboxylic acid,6-methyl-2-pyridone (1/2), C14H10O4·2C6H7NO, (I,d), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol,1-methyl-2-pyridone (1/2), C30H22O2·2C6H7NO, (II,b), 1,1,6,6-tetraphenyl-2,4-hexadiyne-1,6-diol,4-methy-2-pyridone (1/2), C30H22O2·2C6H7NO, (II,c), and 4,4,,4,,-(ethane-1,1,1-triyl)triphenol,6-methyl-2-pyridone,water (1/3/1), C20H18O3·3C6H7NO·H2O, (III,d). In two of the compounds, (I,a) and (I,d), the host molecules lie about crystallographic twofold axes. In two other compounds, (II,b) and (II,c), the host molecules lie across inversion centers. In all cases, the guest molecules are hydrogen bonded to the host molecules through O,H...O=C hydrogen bonds [the range of O...O distances is 2.543,(2),2.843,(2),Å. The pyridone moieties form dimers through N,H...O=C hydrogen bonds in five of the compounds [the range of N...O distances is 2.763,(2),2.968,(2),Å]. In four compounds, (I,a), (I,c), (I,d) and (II,c), the molecules are arranged in extended zigzag chains formed via host,guest hydrogen bonding. In five of the compounds, the guest molecules are arranged in parallel pairs on top of each other, related by inversion centers. However, none of these compounds underwent photodimerization in the solid state upon irradiation. In one of the crystalline compounds, (III,d), the guest molecules are arranged in stacks with one disordered molecule. The unsuccessful dimerization is attributed to the large interatomic distances between the potentially reactive atoms [the range of distances is 4.027,(4),4.865,(4),Å] and to the bad overlap, expressed by the lateral shift between the orbitals of these atoms [the range of the shifts from perfect overlap is 1.727,(4),3.324,(4),Å]. The bad overlap and large distances between potentially photoreactive atoms are attributed to the hydrogen-bonding schemes, because the interactions involved in hydrogen bonding are stronger than those in ,,, interactions. [source]

Synthesis, crystal structure and spectroscopic properties of a novel carbacylamidophosphate: N -(3-nitrobenzoyl)- N,,N,,-bis(tert -butyl)phosphoric triamide

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2009
Khodayar Gholivand
The new compound N -(3-nitrobenzoyl)- N,,N,,-bis(tert -butyl)phosphoric triamide was synthesized by reacting 3-nitrobenzoyl phosphoramidic dichloride and tert -butyl amine, and characterized by multinuclear (1H, 13C and 31P) NMR and FTIR spectroscopy techniques. Structural and conformational properties were analyzed using single-crystal X-ray diffraction, vibrational spectra and theoretical calculations. The crystal structure contains three symmetry-independent disordered molecules, connected via intermolecular N,H...O=P and N,H...O=C hydrogen bonds to form a centrosymmetric hexameric chain extended along the [2,1,] direction. The disorder is mainly caused by rotation of the tert -butyl groups around the C,N bonds. [source]

(E)-3-(4-Methylphenyl)-2-(2-thienyl)acrylonitrile has Z, = 0.75 in the space group C2/m: fourfold disordered molecules lie in channels enclosed by fully ordered molecules

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009
Debora Cobo
The title compound, C14H11NS, crystallizes with Z, = 0.75 in the space group C2/m. Two independent molecules are present, one of which lies with all the non-H atoms on a mirror plane, while the other is fourfold disordered across a site of 2/m symmetry. The ordered molecules are stacked such that they enclose continuous channels running along twofold rotation axes, and the disordered molecules are positioned within these channels. [source]