Molecular Structure and Spectroscopic Signatures of Acrolein: Theory Meets Experiment

Abstract

A comprehensive study of the molecular structure and IR spectrum of cis and trans acrolein has been performed by an integrated computational approach coupling methods rooted in the coupled-cluster ansatz and the density functional theory. From the one side, DFT anharmonic force fields allow us to determine very reliable semiexperimental structures for both isomers, which are in remarkable agreement with the geometries issuing from CCSD(T) computations accounting for the extrapolation to the complete basis set and core correlation. The same kind of coupled-cluster computations provide dipole moment, relative energies, and interconversion barrier in remarkable agreement with experiments. Finally, harmonic CCSD(T) results coupled to DFT evaluation of mechanical and electrical anharmonicity allow us, in the framework of second-order perturbative vibrational theory, to confirm most of the experimental assignments of IR spectra, and to suggest some additional interpretations for congested regions including fundamental bands together with overtones and combination bands.

Adsorption of acrolein, propanal, and allyl alcohol on Pd(111): a combined infrared reflection–absorption spectroscopy and temperature programmed desorption study

“…Previously, most studies assigned the higher wavenumber peak to the aldehyde-C–H group and the lower frequency peak to the vinyl-C–H group; 12 , 13 , 16 , 18 however, we also found the reversed assignment. 14 In literature, the C–C stretching was observed at 1169–1158 cm –1 13 – 16 and the CH 2 scissor deformation in acrolein was reported near 1425 cm –1 . 13 , 14 , 16 The strong IR absorption near 975–990 cm –1 was related to the HC CH 2 unit; however, previous publications assigned these features to different modes, such as CH bend, 15 , 16 CH 2 wag 16 or CH 2 twist 17 vibrations.…”

“… 14 In literature, the C–C stretching was observed at 1169–1158 cm –1 13 – 16 and the CH 2 scissor deformation in acrolein was reported near 1425 cm –1 . 13 , 14 , 16 The strong IR absorption near 975–990 cm –1 was related to the HC CH 2 unit; however, previous publications assigned these features to different modes, such as CH bend, 15 , 16 CH 2 wag 16 or CH 2 twist 17 vibrations. Colthup et al referred to this intense IR absorption as HC CH 2 trans -wag mode.…”

“…Several IR absorption features were found to significantly change from trans - to cis -acrolein. 14 However, Puzzari assigned IR absorption features of vinyl- and aldehyde-C–H bend modes in a way opposite to Hamdada, 13 Fujii, 15 and Akita. 16 Fujii et al 15 and Akita et al 16 investigated the structures of acrolein after adsorption on silver and gold films under UHV conditions.…”

Structure determination of trans-cinnamaldehyde by broadband microwave spectroscopy

“…Using microwave spectroscopy, 17 the structures of both the s-cis-and s-trans-conformers of acrolein were obtained, with a calculated energy difference of 8.5 kJ mol À1 and a calculated barrier height of 29.3 kJ mol À1 (CCSD(T)/CBS+CV). 18 This similarity might hint at the dominance of the local electronic environment in the side chain of transcinnamaldehyde.…”

Computational challenges in Astrochemistry

“…As a matter of fact, benchmark studies suggest that for larger systems, whenever the evaluation of the harmonic PES by means of composite schemes becomes prohibitively expensive, the B2PLYP functional in conjunction with basis sets of at least triple‐ ζ quality provides an effective route for both rotational and vibrational spectroscopy investigations to be compared with an accuracy of 4–10 cm −1 obtained when using harmonic PESs of CCSD(T)/CBS + CV quality .…”