AI Article Synopsis
- The study examines the formation of binary complexes between 2,6-difluorophenylacetylene and four different amines using advanced spectroscopic techniques and calculations.
- All four amines create hydrogen-bonded complexes characterized as CAc-H···N, while trimethylamine and triethylamine also exhibit Lp···π interactions due to the phenyl ring's electron deficiency.
- Energy analysis indicates that hydrogen bonding is favored, although the Lp···π structure in trimethylamine is energetically higher, and the research explains fragmentation of these complexes through intermolecular coulombic decay following ionization.
Article Abstract
Binary complexes of 2,6-difluorophenylacetylene with methylamine, dimethylamine, trimethylamine and triethylamine were investigated using one colour resonant two photon ionization and infrared-optical double resonance spectroscopic techniques combined with high level ab initio calculations. All four amines form CAc-H···N hydrogen-bonded complexes. Additionally trimethylamine and triethylamine form complexes characterized by Lp···π interactions, due to the electron deficient nature of the phenyl ring of 2,6-difluorophenylacetylene. The Lp···π interacting structure of the 2,6-difluorophenylacetylene-trimethylamine complex is about 1.5 kJ mol(-1) higher in energy than the CAc-H···N hydrogen-bonded structure, which is the global minimum. Energy decomposition analysis indicates that the electrostatics and dispersion interactions favour the formation of CAc-H···N and Lp···π complexes, respectively. Interestingly the CAc-H···N hydrogen-bonded complex of 2,6-difluorophenylacetylene-triethylamine showed a smaller shift in the acetylenic C-H stretching frequency than the 2,6-difluorophenylacetylene-trimethylamine complex. The observed fragmentation of the binary complexes of 2,6-difluorophenylacetylene with the four amines following resonant two-photon ionization can be explained on the basis of the intermolecular coulombic decay process.
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| http://dx.doi.org/10.1039/c4cp03445g | DOI Listing |
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