Experimental Charge-Density Study of the Intra- and Intermolecular Bonding in TKX-50
Jeremiah P Tidey1, Vladimir V Zhurov1, Christopher G Gianopoulos1
1University of Toledo , 2801 West Bancroft Street, Toledo, Ohio 43606, United States.
The Journal of Physical Chemistry. A
|November 1, 2017
Summary
This study analyzes bonding in TKX-50 using X-ray diffraction and DFT. Results reveal a layered structure with significant hydrogen bonding and anharmonic motion crucial for accurate modeling.
Area of Science:
- Crystallography
- Quantum Chemistry
- Materials Science
Background:
- Understanding the bonding in energetic materials like dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) is crucial for predicting their properties.
- Experimental charge density analysis provides detailed insights into intra- and intermolecular interactions.
Purpose of the Study:
- To analyze the intra- and intermolecular bonding in TKX-50.
- To compare experimental charge density with DFT calculations.
- To investigate the role of anharmonic motion in modeling TKX-50.
Main Methods:
- High-resolution X-ray diffraction at 20 K to determine experimental charge density.
- Density Functional Theory (DFT) calculations with periodic boundary conditions.
- Topological analysis of electron density.
- Anharmonic and harmonic refinement of structural models.
Main Results:
- TKX-50 exhibits a layered structure predominantly linked by hydrogen bonds and other interactions.
- A pair of 1,5-type intramolecular closed-shell interactions were identified in the dianion.
- Anharmonic motion refinement was essential for an adequate model, significantly improving accuracy over harmonic refinement.
Conclusions:
- The bonding in TKX-50 is characterized by a layered structure with dominant hydrogen bonding.
- Anharmonic motion plays a critical role in accurately describing the electron density distribution in TKX-50.
- The study highlights the importance of advanced refinement techniques for understanding energetic materials.
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