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2 Polish Journal of Chemistry

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Structure and Hydrogen Bonding of Solid N1-Alkyl-N2-(2-hydroxy, 4- or 5-methylphenyl)thioureas

Wawer I., Anulewicz-Ostrowska R., Maciejewska D., Koleva V.

Polish Journal of Chemistry

2000

Vol. 74, nr 6

823-835

Crystalline N1-alkyl-N2-arylthioureas with ortho hydroxyl and para or meta methyl substituents to the phenyl ring were studied by single crystal X-ray diffraction, IR and solid state 13C cP MAS NMR. Two different modes of association were found: i) intermolecular N1H...S bonds and N2H not involved in hydrogen bonding in N1-methyl-N2-(2-hydroxy, 5-metylphenyl)thuiourea 1, ii) cyclic dimers with two N2H...S hydrogen bonds (S...N2 distance of 3.332 A) and N1H engaged in intermolecular N1H...O bond in N1-methyl-N2-(2-hydroxy,4 methylphenyl)thiourea 2. Changes of carbon chemical shifts between solution and solid state result mainly from the reorientation of the aromatic ring with respect to the thiourea fragent.

(13)C CP MAS NMR study of some 4,4'-disubstituted-trans-azobenzenes

Maciejewska D., Koleva V., Wawer I.

Polish Journal of Chemistry

1998

Vol. 72, nr 12

2531-2536

Azobenzenes with para-dimethylamino group at aromatic ring and various para substitutes to another phenyl have been studied by (13)C CP MAS NMR spetroscopy followed by semi-empirical AMI MO calculations. The locked trans-configuration around N=N bond in the state results in non-equivalence of ortho carbons (C2 and C6, also C2' and C6') and the diference in chemical shifts is 12.9-22.0 ppm. The separation of meta carbons resonances is less manifested but in 1, 3, 4, 8 the non-equivalence of C3' and C5' is enhanced by the orientation of X-substituents at C4'.