From rotational resolved spectra to an extended increment system of planar moments allowing ad-hoc conformational identification – Exemplification by the broadband microwave spectrum of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mi>α</mml:mi></mml:math>-hydroxyisobutyric acid

Buschmann, Philipp; Lengsfeld, Kevin G.; Djahandideh, Jasmin; Grabow, Jens‐Uwe

doi:10.1016/j.molstruc.2021.131805

Cited by 3 publications

(2 citation statements)

References 204 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, we could consider also a comparison with any molecules possessing two out-of-plane hydrogen atoms. Exemplarily, as summarized by Buschmann et al [31], the 0 value found for vanillin, a molecule of similar size as benzyl cyanide and also featuring a phenyl ring, is −3.56 uÅ 2 for the a-cis-trans conformer and −3.74 uÅ 2 for the a-trans-trans conformer [32]. The values of methyl vinyl sulfide [33] and methyl vinyl ether [34] are −3.14 uÅ 2 and −3.18 uÅ 2 , respectively.…”

Section: Planar or Not Planar?mentioning

confidence: 99%

On the planarity of benzyl cyanide

Tran

Errouane

Condon

et al. 2022

Journal of Molecular Spectroscopy

View full text Add to dashboard Cite

Section: Planar or Not Planar?mentioning

confidence: 99%

On the planarity of benzyl cyanide

Tran

Errouane

Condon

et al. 2022

Journal of Molecular Spectroscopy

View full text Add to dashboard Cite

“…compared its value with those obtained for other aromatic molecules containing one methyl group. As recently summarized by Buschmann et al, conformers exhibiting Cs symmetry with only two methyl hydrogen atoms with out-of-plane contributions feature an inertial defect of -3.2 uÅ², with experimental values varying from about -3.0 uÅ² to -3.7 uÅ²[53]. The values obtained for the three isomers of methylthiazole are all close to -3.1 uÅ², i.e.…”

mentioning

confidence: 59%

Influence of π-electron conjugation outside the aromatic ring on the methyl internal rotation of 4-methyl-5-vinylthiazole

et al. 2022

View full text Add to dashboard Cite

The microwave spectrum of 4-methyl-5-vinylthiazole was measured using a pulsed molecular jet Fourier transform microwave spectrometer operating in the frequency range from 2.0 to 26.5GHz. Only the anti-conformer was observed. Due to internal rotation of the methyl group, doublets containing an A and an E torsional species were found for all rotational transitions. Hyperfine structures arising from the 14 N nuclear quadrupole coupling were resolved. The complex spectral patterns were analysed and fitted using the XIAM and BELGI-Cs-hyperfine codes, yielding a barrier to methyl internal rotation of 107.0901(7) cm −1 and the quadrupole coupling constants 𝜒 𝑎𝑎 = −3.545(13), 𝜒 𝑏𝑏 − 𝜒 𝑐𝑐 = −1.563(24) and 𝜒 𝑎𝑏 = −1.76(11) MHz. The experimental results were supported by data from quantum chemistry. Some calculations using the MP2 method yielded non-planar structures, where the vinyl group is tilted out of the thiazole ring plane. The inertial defect and the 𝜒 𝑐𝑐 constant were compared with those obtained for other aromatic molecules to support the planarity of the 4-methyl-5-vinylthiazole. A comparison of the methyl torsional barrier with other thiazole derivatives suggests that electrostatic effects caused by the π-conjugated system of thiazole extended by the vinyl group are the reason of the low torsional barrier of the methyl group.

show abstract