Measurement and analysis of the infrared absorption spectrum of the radical cation of [34](1,2,4,5)cyclophane: Observation of electron–molecular vibration interaction between two benzene moieties

• Published in: Chemical physics Vol. 419; pp. 266 - 273
• Main Authors: Sakamoto, Akira, Tanaka, Nobuki, Shinmyozu, Teruo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20-06-2013
• Subjects: Cyclophane; Electron–molecular vibration interaction; Infrared absorption spectra; Radical cation; Electron–molecular vibration interaction; Radical cation; Cyclophane; Infrared absorption spectra
• ISSN: 0301-0104
• DOI: 10.1016/j.chemphys.2013.03.018

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•An IR spectrum has been observed for the radical cation of [34](1,2,4,5)cyclophane.•The observed IR spectrum is in good agreement with that calculated by DFT.•The origin of the large IR intensities is discussed in terms of EMV interaction.
A high-quality infrared absorption spectrum has been observed for the radical cation of [34](1,2,4,5)cyclophane in a dichloromethane solution by using a Fourier-transform infrared spectrometer contained in an inert gas glovebox system. The structures and vibrational properties (harmonic frequencies, vibrational modes, and infrared intensities) have been calculated for the neutral species and radical cation of [34](1,2,4,5)cyclophane by density functional theory at the B3LYP/6-311+G(d,p) level. The observed infrared spectra of the neutral species and radical cation are in good agreement with those calculated. Some specific vibrational modes of the radical cation have large infrared absorption intensities. The origin of the large infrared absorption intensities characteristic of the radical cation is discussed in terms of electron–molecular vibration interaction (changes in electronic structure induced by specific normal vibrations) between two benzene moieties of [34](1,2,4,5)cyclophane.