Derivatives of benzobfuran. Part II. Structural studies of derivatives of 2- and 3-benzobfurancarboxylic acidsReport as inadecuate

Derivatives of benzobfuran. Part II. Structural studies of derivatives of 2- and 3-benzobfurancarboxylic acids - Download this document for free, or read online. Document in PDF available to download.

Structural Chemistry

, Volume 23, Issue 5, pp 1617–1629

First Online: 24 February 2012Received: 16 November 2011Accepted: 29 January 2012

AbstractThe selected derivatives of the 2- and 3-benzobfurancarboxylic acids were synthesized and their structures were studied using the X-ray crystallography and the computational methods. The monocarboxylic acids 1 –3 crystallize as dimers stabilized by the O–H···O intermolecular hydrogen bonds. Moreover, intramolecular hydrogen bonds are formed between the OH and C=OCH3 groups, substituted to the aromatic ring 2 –4 . In the crystal structures of 1 –4 , weak C–H···O, C–H···π, and C–H···Br interactions stabilize the three-dimensional packing of molecules. The crystalline sodium complex of 1 has the stoichiometry Na ·1A ·1B ·1C , thus, the asymmetric unit contains three different moieties of 1 . In this complex, the Na cation is hexacoordinated having a strongly distorted tetragonal bipyramidal polyhedron. For each molecule 1 –4 , several conformers were obtained in the gas phase. It was achieved by the rotations of substituents COOR and-or C=OCH3, where R = H, CH3 with respect to the rigid benzobfuran system. As indicated by the quantum-chemical calculations, the solid-state conformers for 3 and 4 3-benzobfurancarboxylic acid derivatives are the most stable ones. In contrast, the solid-state conformers of the 2-benzobfurancarboxylic acid derivatives 1 , 2 have the energies higher than the lowest energy conformer by 1.23 and 0.69 kcal-mol, respectively. It seems that intermolecular contacts in the crystal influence on the orientation of substituents, and the conformers observed in the sodium complex of 1 provide evidence of such flexibility.


Abstract Hirshfeld surface for a pair of molecules 2A-2B bromo-derivative.Open image in new windowKeywordsBenzobfuran derivatives Conformational analysis Theoretical calculations Crystal structure Electronic supplementary materialThe online version of this article doi:10.1007-s11224-012-9965-6 contains supplementary material, which is available to authorized users.

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Author: Aleksandra Drzewiecka - Anna E. Koziol - Tomas Pena Ruiz - Manuel Fernandez Gomez - Marta Struga - Jerzy Kossakowski - King


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