The vibrational absorption spectra and vibrational circular dichroism (VCD) spectra of both enantiomers of
4-X-[2.2]paracyclophanes (X ) COOCD3, Cl, I) have been recorded for a few regions in the range of 900-
12000 cm-1. The analysis of the VCD spectra for the two IR regions, 900-1600 cm-1 and 2800-3200 cm-1,
is conducted by comparing with DFT calculations of the corresponding spectra; the latter region reveals
common motifs of vibrational modes for the three molecules for aliphatic CH stretching fundamentals, whereas
in the mid-IR region, one is able to identify specific signatures arising from the substituent groups X. In the
CH stretching region between 2900 and 2800 cm-1, we identify and interpret a group of three IR VCD bands
due to HCH bending overtone transitions in Fermi resonance with CH stretching fundamental transitions.
The analysis of the NIR region between 8000 and 9000 cm-1 for X ) COOCD3 reveals important features
of the aromatic CH stretching overtones that are of value since the aromatic CH stretching fundamentals are
almost silent. The intensifying of such overtones is attributed to electrical anharmonicity terms, which are
evaluated here by ab initio methods and compared with literature data
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