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4-Chloro-2',4',6'-triethyl-benzophenone: a redetermination.
1Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
Summary
This study redetermined the crystal structure of (4-chloro-phenyl)(2,4,6-trimethyl-phenyl)methanone at 100 K. Higher precision revealed ethyl group disorder, explaining the absence of a polymorphic phase transition.
Area of Science:
- Crystallography
- Solid-state chemistry
Background:
- Previous crystal structure determination of (4-chloro-phenyl)(2,4,6-trimethyl-phenyl)methanone was at 133 K.
- A closely related compound exhibited a single-crystal-to-single-crystal polymorphic phase transition upon cooling.
Purpose of the Study:
- To redetermine the crystal structure of (4-chloro-phenyl)(2,4,6-trimethyl-phenyl)methanone at 100 K with higher precision.
- To investigate the cause of the absence of a polymorphic phase transition in the title compound.
Main Methods:
- Single-crystal X-ray diffraction at 100 K.
- Structure refinement with high precision.
Main Results:
- The crystal structure of (4-chloro-phenyl)(2,4,6-trimethyl-phenyl)methanone was redetermined at 100 K.
- Disorder in one of the ortho-ethyl groups was identified with occupancy factors of 0.77(1) and 0.23(1).
- The C-C-C-C torsion angles for the ethyl group disorder components were -103.7(2)° and -172.0(6)°.
Conclusions:
- The identified ethyl group disorder explains the lack of a single-crystal-to-single-crystal polymorphic phase transition upon cooling.
- The higher precision of the 100 K structure determination was crucial for revealing the subtle disorder.
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