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Published on: October 27, 2018
5-Iodobenzofurazan 1-oxide: polymorphs, pseudosymmetry and disorder
Doyle Britton1, Wayland E Noland, Christopher M Clark
1Department of Chemistry, University of Minnesota, Minneapolis, MN 55455-0431, USA. britton@chem.umn.edu
Summary
Two polymorphic forms of 5-iodobenzofurazan 1-oxide exhibit distinct intermolecular interactions. Polymorph I features strong iodine-oxygen bonds, while polymorph II shows strong iodine-nitrogen bonds, impacting crystal structures.
Area of Science:
- Crystallography
- Solid-state chemistry
Background:
- 5-Iodobenzofurazan 1-oxide is a chemical compound with the formula C(6)H(3)IN(2)O(2).
- Polymorphism, the ability of a solid material to exist in more than one form or crystal structure, is common in organic compounds.
Purpose of the Study:
- To investigate the crystal structures and intermolecular interactions of 5-iodobenzofurazan 1-oxide.
- To compare the distinct polymorphic forms of 5-iodobenzofurazan 1-oxide.
Main Methods:
- Single-crystal X-ray diffraction was used to determine the crystal structures of the two polymorphs.
- Analysis of intermolecular distances and angles to characterize interactions.
Main Results:
- Two monoclinic polymorphic forms (P2(1)/c, Z'=2) of 5-iodobenzofurazan 1-oxide were identified.
- Polymorph I exhibits strong intermolecular iodine-oxygen (I...O) interactions (3.114-3.045 Å).
- Polymorph II displays strong intermolecular iodine-nitrogen (I...N) interactions (3.163-3.175 Å).
- Disorder was observed in polymorph I (15% and 5%).
- Pseudosymmetric relationships exist between crystallographically independent molecules in both polymorphs.
Conclusions:
- The polymorphic forms of 5-iodobenzofurazan 1-oxide are differentiated by their dominant intermolecular interactions (I...O vs. I...N).
- These distinct interactions dictate the crystal packing and properties of each polymorph.
- Understanding these interactions is crucial for controlling solid-state properties and potential applications.
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