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Crystallographic Studies and Physico-Chemical Properties of n-Electron Compounds. Part II. Crystal and Molecular Structure of 2,4-Dinitrobenzoic Acid (DNBA)

Tadeusz Wieckowski ; Department of Chemistry, University of Warsaw, 02093 Warsaw, ul. Pasteura 1, . Poland
Tadeusz M. Krygowski ; Department of Chemistry, University of Warsaw, 02093 Warsaw, ul. Pasteura 1, . Poland


Puni tekst: engleski pdf 4.214 Kb

str. 5-14

preuzimanja: 246

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Sažetak

The crystal structure of the title compound has been determined
by single-crystal X-ray diffraction studies from 1043 reflections.
The crystals are monoclinic with a = 6.2150(7)A b = 14.393(2)
A, and c = 9.487(1)A, fJ = 97.175(9)°,space group Pž-f c, and Z = 4.
The structure was solved by direct methods and refined by fullmatrix
least-squares to a final R = 0.050. The molecule are paired by hydrogen bonding between the carboxy-groups (O-H ... O 2.656(3)A), the two halves of the dimer being related by a centre of symmetry. It was found that the planes of the two carboxy-groups in the dimer are separated by a distance 0.113A. The significant difference between (leooHvalues for para substituted benzoic acids with a-electron withdrawing and -releasing substituents, 1.4(1)°,was found.
The Lippincott-Schroeder model-" was applied to describe the properties of the H-bridge in DNBA and six other, accurately
determined, crystal structures of para-substituted benzoic acids.
The amplitudes of internal motion of the substituents are estimated in terms of the Dunitz and White model.

Ključne riječi

Hrčak ID:

177735

URI

https://hrcak.srce.hr/177735

Posjeta: 443 *