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Magnetic Interactions in Cu(pyridine-2-carboxylate)2

Żurowska B., Mroziński J., Ciunik Z.

Polish Journal of Chemistry

2007

Vol. 81, nr 3

403-410

The magnetic properties of the compound of the formula Cu(2-pca)2, (2-pca = 2-picolinate ion) were studied in the light of its known X-ray structure. The crystal structure consists of a copper atom lying in the centre of symmetry, trans square-planar coordinated via two pyridine nitrogens and the carboxylate oxygen atoms of the two picolinate anions. The crystal packing is due to short pi-pi stacking interactions between pyridine rings belonging to different molecules giving rise to a one-dimensional polymeric network arrangement. Additional CH-O hydrogen bonds form a three-dimensional polymeric network. The variable-temperature (1.8-300 K) magnetic susceptibility data of the complex were interpreted with the Bonner-Fisher expression with molecular field approximation, yielding J, zJ' and g values of -0.76, -0.47 cm-1, 2.09, respectively. The magnitude of the magnetic interaction through the pi-pi stacking interaction and hydrogen bond, and the nature of the exchange coupling is discussed on the basis of the structural data results.

1H, 13C and 15N NMR Spectral and X-ray Structural Studies of 2-Arylsulfonylamino-5-chlorobenzophenones

Kolehmainen E., Nissinen M., Janota H., Gawinecki R., Ośmiałowski B.

Polish Journal of Chemistry

2003

Vol. 77 / nr 7

889-894

Six 2-(4-R-phenylsulfonylamino)-5-chlorobenzophenones were prepared and their 1H, 13Cand 15NNMRspectra recorded and assigned. The dependence between the chemical shift of the amide proton and Hammett _ substituent constants is of the V type. Substituent effect on the chemical shift of the amide nitrogen atom was found insignificant. X-ray analysis shows that the terminal benzene rings in 2-(4-nitrophenylsulfonylamino)-5-chlorobenzophenone are located close to each other. They are not, however, parallel, dihedral angle between them being equal to 10.86 deg (MP2/6-31G**//HF/6-31G** ab initio calculations show this to be 20.44 deg). This shows that the mutual orientation of two benzene rings in the molecule of this compound is caused by the _-_ stacking. It is additionally reinforced by the intramolecular NH…O=C hydrogen bond. Except the dihedral angle between the benzene rings, X-ray determined structure of 2-(4-nitrophenylsulfonylamino)-5-chlorobenzophenone is very similar to this optimized by the ab initio calculations.