Abstract
CH stretching vibrations of jet-cooled benzene-acetylene and several aromatics-acetylene clusters were observed in order to characterize the intermolecular interaction, so-called activated CH/π interaction between an acidic CH group and π-electrons. The infrared-ultraviolet double resonance spectroscopic techniques were used for measuring their vibrational spectra. The antisymmetric CH stretching vibration of the acetylene moiety exhibits a remarkable low-frequency shift upon the cluster formation with the aromatic molecules, indicating such a cluster structure that the acetylenic CH group is bound to π-electrons of the aromatic ring. The low-frequency shifts observed for the clusters show a positive correlation with the π-electron density of the ring, as expected for an ordinary π-hydrogen bond. On the other hand, the polarizability of the proton-accepting molecules showed a weakly negative correlation with the CH frequency shifts. These results show that the intermolecular interaction between the activated CH group and π-electrons is characterized as a π-hydrogen bond rather than as a van der Waals interaction.
Original language | English |
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Pages (from-to) | 2652-2658 |
Number of pages | 7 |
Journal | Journal of Physical Chemistry A |
Volume | 108 |
Issue number | 14 |
DOIs | |
Publication status | Published - 2004 Apr 8 |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry