Orientational disorder in 4-chloronitrobenzene.
Lynne H Thomas1, Jacqueline M Cole, Chick C Wilson
1Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, England.
Summary
This study re-examines the crystal structure of 4-chloronitrobenzene, revealing twofold orientational disorder and significant thermal motion. These findings clarify structural anomalies in this solid-state material.
Area of Science:
- Solid-state chemistry
- Crystallography
- Materials science
Background:
- 4-Chloronitrobenzene exhibits structural anomalies in its solid state.
- Previous crystal structure determinations lacked comprehensive data.
Purpose of the Study:
- To re-examine the crystal structure of 4-chloronitrobenzene.
- To rationalize observed structural anomalies using multiple temperature data.
- To provide an improved crystal structure determination.
Main Methods:
- Multiple-temperature single-crystal X-ray diffraction.
- Analysis of crystallographic data to identify disorder and thermal motion.
Main Results:
- A marked improvement on previous crystal structure determinations was achieved.
- Twofold orientational disorder of the nitro (NO2) and chlorine (Cl) substituents was confirmed.
- Significant large-amplitude thermal motion was observed across all temperatures, indicating substantial disorder.
- The nitro group exhibits libration, with one oxygen atom showing greater thermal motion due to differing hydrogen-bonding environments.
Conclusions:
- The re-examined crystal structure provides a clearer understanding of 4-chloronitrobenzene's solid-state behavior.
- Multiple-temperature diffraction data effectively explains the observed structural anomalies.
- The study highlights the presence and nature of significant disorder in 4-chloronitrobenzene.
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