Journal
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 23, Issue 14, Pages 8549-8556Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1cp00188d
Keywords
-
Funding
- Canada Foundation for Innovation (CFI)
- Natural Sciences and Engineering Research Council (NSERC)
- National Research Council (NRC)
- Canadian Institutes of Health Research (CIHR)
- Government of Saskatchewan
- University of Saskatchewan
- Fundamental Research Funds for Chinese Central Universities [lzujbky-2019-65, lzujbky-2019-ct05]
- Lanzhou University
- Cuiying Honors College, Lanzhou University
Ask authors/readers for more resources
This study reports the torsional vibrational spectra of benzaldehyde based on high resolution spectroscopic investigation, aiming to eliminate experimental ambiguity. The experimental determination of the barrier to internal rotation was lower compared to theoretical calculations, indicating the discrepancy between theory and experiment remains despite best efforts.
A discrepancy between theoretical and experimental values of the rotational barrier in benzaldehyde has been observed, which was attributed to inaccurate experimental results in part. Here, we report results on the -CHO torsion of benzaldehyde (C6H5CHO) based on a high resolution spectroscopic investigation in the far-infrared range in an effort to remove the experimental ambiguity. The rotationally-resolved vibrational spectra were measured with an unapodized resolution of 0.00064 cm(-1) using synchrotron-based Fourier transform infrared (FTIR) spectroscopy at the Canadian Light Source. The torsional fundamental nu(t) = 109.415429(20) cm(-1) was unambiguously assigned via rovibrational analysis, followed by the tentative assignment of the first (2 nu(t) - nu(t)) and second (3 nu(t) - 2 nu(t)) hot bands at 107.58 cm(-1) and 105.61 cm(-1), respectively, by comparison of the observed Q branch structures at high resolution with simulation based on a previous microwave study. This assignment is different from any previous low resolution infrared studies in which the intensity patterns were misleading. The key result of the assignment of the first three transitions allowed the determination of the barrier to internal rotation of (hc)1533.6 cm(-1) (4.38 kcal mol(-1)). When compared with calculated results from vibrational second-order perturbation theory (VPT2) and the quasiadiabatic channel reaction path Hamiltonian (RPH) approach, the experimental value is still too low and this suggests that the discrepancy between theory and experiment remains despite the best experimental efforts.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available