Internal dynamics in azetidine: A microwave and <i>ab initio</i> study

López, Juan C.; Blanco, Susana; Lesarri, Alberto; Alonso, José L.

doi:10.1063/1.1334876

Cited by 14 publications

(73 citation statements)

References 36 publications

(42 reference statements)

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“…As c-type bands have sharp Q branches, we studied this region of our spectrum closely but did not find such transitions. The infrared study of Egawa and Kuchitsu [15] reported that coupling of the NH inversion and ring puckering motions was only significant in the deuterated isotopologue of azetidine but based on the quality of the more recent microwave [17] investigation which clearly shows the presence of this coupling, we assert that the lack of observed c-type transitions in our infrared spectrum is due to insufficient intensity compared to the dominant a-type transitions.…”

Section: Symmetry Considerations and Nh Inversion Tunnelingmentioning

confidence: 64%

“…The ground state rotational constants determined in this work are compared to those from the microwave investigation of López et al [17] in Table 2. In the microwave spectrum, the ground state and m 16 excited state rotational transitions were doubled.…”

Section: The Ground State Of Azetidinementioning

confidence: 98%

“…Based on the similarity in the rotational constants determined for the NH inversion tunneling states in Ref. [17] (which differ by a few kHz or less), the a-and c-type transitions will not be doubled in the infrared spectrum as the calculated splittings fall below the resolution of the spectrometer.…”

Section: Spectral Assignment and Analysismentioning

confidence: 99%

“…The microwave spectrum of the ground state and several excited ring puckering states of azetidine was analyzed in terms of the C 2v molecular symmetry group to allow for the description of the observed NH inversion tunneling splittings [17]. This led to the determination of two sets of spectroscopic constants for each vibrational state corresponding to symmetric (A 1 ) and antisymmetric (B 1 ) inversion tunneling components.…”

Section: Spectral Assignment and Analysismentioning

confidence: 99%

“…The microwave and electron diffraction experiments of Günther et al [16] confirmed the presence of the equatorial conformer and determined its structure to have a ring puckering angle of 29.7°although their microwave spectrum also contained a weak unassigned feature which was thought to be due to the axial conformer. The more recent microwave and ab initio investigation of López et al [17] analyzed the rotational spectrum in the ground and several excited ring puckering vibrational states. Their results point to a single well asymmetric potential along the ring puckering coordinate.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

Zaporozan

Chen

Wijngaarden

2010

Journal of Molecular Spectroscopy

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Section: Symmetry Considerations and Nh Inversion Tunnelingmentioning

confidence: 64%

Section: The Ground State Of Azetidinementioning

confidence: 98%

Section: Spectral Assignment and Analysismentioning

confidence: 99%

Section: Spectral Assignment and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

Zaporozan

Chen

Wijngaarden

2010

Journal of Molecular Spectroscopy

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Effects of ring contraction on the conformational preferences of α‐substituted proline analogs

et al. 2011

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The structural consequences derived from the incorporation of either a methyl or a phenyl group at the α carbon of proline were recently investigated by quantum mechanical calculations (J Org Chem 2008, 73, 3418). In this work, the effect produced by contraction of the pyrrolidine ring on such α-substituted proline analogs has been explored using the same computational methods. Specifically, the intrinsic conformational preferences of the N-acetyl-N'-methylamide derivatives of the lower proline homolog L-azetidine-2-carboxylic acid (Aze), characterized by a four- instead of a five-membered ring, and its α-methyl (αMeAze) and α-phenyl (αPhAze) derivatives have been determined using quantum mechanical calculations and compared to those observed before for the proline counterparts. Replacement of the pyrrolidine ring by an azetidine cycle leads to a reduction of the conformational flexibility, especially for the Aze and αMeAze derivatives, which should be attributed to the quasi-planar geometry of the four-membered ring. Furthermore, the azetidine nitrogen shows pyramidalization, which depending on the peptide backbone conformation favors the formation of an attractive N-H···N interaction or alleviates a severe steric hindrance. Calculations on different environments predict that the tendency of αMeAze to adopt γ-turns is higher than that of unsubstituted Aze and α-methylproline, this feature being in full agreement with the experimental observations available.

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Targeting the Rich Conformational Landscape of N‐Allylmethylamine Using Rotational Spectroscopy and Quantum Mechanical Calculations

2020

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The highly variable conformational landscape of N-allylmethylamine (AMA) was investigated using Fourier transform microwave spectroscopy aided by high-level theoretical calculations to understand the energy relationship governing the interconversion between nine stable conformers. Spectroscopically, transitions belonging to four low energy conformers were identified and their hyperfine patterns owing to the 14 N quadrupolar nucleus were unambiguously resolved. The rotational spectrum of the global minimum geometry, conformer I, shows an additional splitting associated with a tunneling motion through an energy barrier interconnecting its enantiomeric forms. A two-step tunneling trajectory is proposed by finding transition state structures corresponding to the allyl torsion and NH inversion. Natural bond orbital and noncovalent interaction analyses reveal that an interplay between steric and hyperconjugative effects rules the conformational preferences of AMA.

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Internal dynamics in azetidine: A microwave and ab initio study

Abstract: Articles you may be interested inMicrowave measurements and ab initio calculations of structural and electronic properties of N -Et-1,2-azaborine Microwave spectroscopic and ab initio studies of the hydrogen-bonded trimethylamine-hydrogen sulfide complex

Cited by 14 publications

References 36 publications

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

Effects of ring contraction on the conformational preferences of α‐substituted proline analogs

Targeting the Rich Conformational Landscape of N‐Allylmethylamine Using Rotational Spectroscopy and Quantum Mechanical Calculations

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