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Published on: May 27, 2015
1-Methylindole-3-carboxaldehyde oxime derivatives
R W Janes1, B S Potter, M A Naylor
1School of Biological Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, England. r.w.janes@qmw.ac.uk
Acta Crystallographica. Section C, Crystal Structure Communications
|February 15, 2001
Summary
Structural analysis of two indole derivatives revealed distinct geometric configurations. 1-Methylindole-3-carboxaldehyde oxime shows cis geometry, while its 5-methoxy analog exhibits trans geometry, influencing crystal packing.
Area of Science:
- Organic Chemistry
- Crystallography
- Molecular Geometry
Background:
- Indole derivatives are prevalent in pharmaceuticals and natural products.
- Understanding the precise molecular geometry of oximes is crucial for predicting their chemical behavior and biological activity.
- The hydroxyimino group's orientation relative to the indole core can significantly impact intermolecular interactions.
Purpose of the Study:
- To determine the crystal structures of 1-methylindole-3-carboxaldehyde oxime and (E)-5-methoxy-1-methylindole-3-carboxaldehyde oxime.
- To ascertain the geometric relationship between the hydroxyimino function and the indole core in these compounds.
- To investigate the role of intermolecular forces, such as hydrogen bonding, in stabilizing the crystal lattices.
Main Methods:
- Single-crystal X-ray diffraction was employed to analyze the three-dimensional structures of both compounds.
- Crystallographic data were collected and refined to determine atomic positions and bond parameters.
- Analysis of the crystal structures focused on the geometry of the oxime group and the arrangement of molecules within the asymmetric unit.
Main Results:
- 1-Methylindole-3-carboxaldehyde oxime (I) was found to exhibit cis geometry around the hydroxyimino group, with two molecules in the asymmetric unit.
- (E)-5-methoxy-1-methylindole-3-carboxaldehyde oxime (II) displayed trans geometry, with four molecules in the asymmetric unit.
- The crystal structures of both oximes are primarily stabilized by hydrogen bonding, with no significant pi-stacking interactions observed between indole moieties.
Conclusions:
- The study elucidates the distinct cis and trans geometries adopted by the hydroxyimino groups in the examined indole derivatives.
- The presence of a 5-methoxy group influences the molecular conformation and the number of molecules within the asymmetric unit.
- Hydrogen bonding plays a dominant role in the crystal packing of these indole oximes, highlighting its importance in supramolecular assembly.
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