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Experimental Reference Data for Hexafluorinated Propanol by Exploring an Unusual Intermolecular Torsional Balance
1Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, 37077, Goettingen, Germany.
Angewandte Chemie (International Ed. in English)
|August 12, 2017
Summary
The hydrogen-bonded dimer of hexafluoro-2-propanol exhibits a unique torsional balance. Dinitrogen coordination shifts this balance, revealing insights into fluorous hydrogen bonding interactions.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) forms hydrogen-bonded dimers with unique structural properties.
- The intermolecular -OH⋅⋅⋅O- bond in HFIP dimers allows for torsional arrangements influenced by external factors.
Purpose of the Study:
- To investigate the conformational preferences of the HFIP dimer.
- To understand how dinitrogen coordination affects the torsional balance of the HFIP dimer.
- To evaluate computational methods for describing fluorous hydrogen bonds.
Main Methods:
- Fourier-transform infrared (FTIR) spectroscopy in supersonic jets.
- Multi-step divide-and-conquer quantum chemical calculations.
- Assessment of various density functional theory (DFT) methods, including B3LYP-D3.
Main Results:
- The free HFIP dimer prefers an arrangement where the acceptor OH group points away from fluorine atoms.
- Dinitrogen coordination to the acceptor OH group favors the arrangement where the OH group points towards fluorine atoms.
- B3LYP-D3 functional provided a satisfactory description of experimental constraints for fluorous hydrogen bonding.
Conclusions:
- Intermolecular torsional balances in hydrogen-bonded systems serve as valuable tools for benchmarking non-covalent interactions.
- Computational methods need careful selection to accurately describe fluorous hydrogen bonds.
- The study provides a detailed understanding of conformational dynamics in HFIP dimers.
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