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Davies AR, Haynes JT, Wright TG. Spectroscopy of N-methylpyrrole-RG (RG = Ar, Kr) complexes: First excited neutral and ground cationic states. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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Gascooke JR, Lawrance WD. Strong Torsion-Vibration Interaction in N-Methylpyrrole Observed by Far-Infrared Spectroscopy. J Phys Chem A 2022; 126:2160-2169. [PMID: 35357831 DOI: 10.1021/acs.jpca.1c10636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An interaction between methyl torsion and the low-lying out-of-plane methyl wag vibration has been observed in toluene, p-fluorotoluene, and m-fluorotoluene, contravening the traditional assumption used when analyzing spectra that methyl torsion can be treated independently of the small-amplitude vibrations. When a methyl group is attached to a planar frame, out-of-plane methyl wag vibrations always occur, and hence this type of interaction between methyl torsion and vibration is potentially extensive. To probe whether this coupling occurs beyond toluene and its derivatives, we have studied the far-infrared absorption band for the out-of-plane methyl wagging mode in N-methylpyrrole. The torsional sequence structure reveals a particularly strong torsion-vibration interaction. Spectral simulations yield a torsion-vibration coupling matrix element of 34.0 cm-1, over twice the value for toluene. The large torsion-vibration coupling constant implies that there is a significant tilting of the methyl group out of plane. Quantum chemistry calculations reveal a much larger out-of-plane methyl tilt angle in N-methylpyrrole compared to toluene, qualitatively consistent with this expectation. This is the first nontoluene derivative for which this type of torsion-vibration interaction has been reported and shows that the effect extends beyond toluenes. When present, this interaction links small-amplitude vibrations to the methyl torsion, providing a mechanism to bring the increased density of states into play and accelerate the rate of intramolecular vibrational energy redistribution.
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Affiliation(s)
- Jason R Gascooke
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Warren D Lawrance
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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Gougoula E, Medcraft C, Heitkämper J, Walker NR. Barriers to internal rotation in methylimidazole isomers determined by rotational spectroscopy. J Chem Phys 2019; 151:144301. [DOI: 10.1063/1.5119997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Eva Gougoula
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Chris Medcraft
- School of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Juliane Heitkämper
- Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Karlsruhe, Germany
| | - Nicholas R. Walker
- Chemistry, School of Natural and Environmental Sciences, Newcastle University, Bedson Building, Newcastle upon Tyne NE1 7RU, United Kingdom
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Robbins TJ, Wang Y, Yao QZ, Wang ZH, Cheng J, Li YS. Vibrational spectra, DFT calculations, and conformations of 5′-chloro-1-isopropyl-7-azaindirubin-3′-oxime. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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5
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Wörmke S, Brendel K, Andresen U, Mäder H. A molecular beam Fourier transform microwave study of 2-methylpyridine and its complex with argon: structure, methyl internal rotation and14N nuclear quadrupole coupling. Mol Phys 2008. [DOI: 10.1080/00268970410001725860] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- S. Wörmke
- a Institut für Physikalische Chemie , Christian-Albrechts-Universitat zu Kiel , Olshausenstr, 40-60, D-24098, Kiel , Germany
| | - K. Brendel
- a Institut für Physikalische Chemie , Christian-Albrechts-Universitat zu Kiel , Olshausenstr, 40-60, D-24098, Kiel , Germany
| | - U. Andresen
- a Institut für Physikalische Chemie , Christian-Albrechts-Universitat zu Kiel , Olshausenstr, 40-60, D-24098, Kiel , Germany
| | - H. Mäder
- a Institut für Physikalische Chemie , Christian-Albrechts-Universitat zu Kiel , Olshausenstr, 40-60, D-24098, Kiel , Germany
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6
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Melandri S, Favero PG, Caminati W, Velino B. Internal dynamics features in the free jet rotational spectrum of the acetaldehyde-Kr molecular complex. J Chem Phys 2005; 122:134310. [PMID: 15847468 DOI: 10.1063/1.1869990] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structure and the dynamics of internal motions in the complex formed between acetaldehyde and Kr are studied by free jet absorption microwave spectroscopy performed in the range 60-78 GHz. The fourfold structure of each rotational line is evidence of the vibration-rotation coupling between the overall rotation of the complex, a tunneling motion of the Kr atom between two equivalent positions and the internal rotation of the methyl group in the acetaldehyde moiety. The four sets of transitions could be fitted with a coupled Hamiltonian which allows for the Coriolis interaction obtaining the energy separation between the vibrational energy levels related to the tunneling motion, while the observed splittings due to the methyl group internal rotation were analyzed independently with an appropriate model. The potential energy barriers for the tunneling motion and the internal rotation of the methyl group have been calculated and the interaction of the rare gas atom with the acetaldehyde moiety is reflected in the change of the V(3) barrier to internal rotation in going from the molecule to the weakly bound complex.
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Affiliation(s)
- S Melandri
- Dipartimento di Chimica G. Ciamician, dell'Università, Via Selmi 2, I-40126 Bologna, Italy.
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Theoretical study of the internal rotational barriers in some N-substituted nitropyrroles. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0166-1280(03)00468-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Biswas N, Wategaonkar S, Philis JG. Geometry and vibrations of N-methylpyrrole in the S0 state studied by dispersed fluorescence spectroscopy and ab initio calculations. Chem Phys 2003. [DOI: 10.1016/s0301-0104(03)00299-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Makarewicz J, Huber S, Brupbacher-Gatehouse B, Bauder A. Internal rotation dependent quadrupole hyperfine splittings of rotational transitions of N-methylpyrrole. J Mol Struct 2002. [DOI: 10.1016/s0022-2860(02)00082-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Merkt F, Quack M. An appreciation of Alfred Bauder. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(01)00816-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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Schäfer M. Weakly bound complexes: structure and internal motion data obtained from rotational spectra. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(01)00838-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Takeuchi H, Inoue K, Enmi J, Hamada T, Shibuya T, Konaka S. Molecular structure of N-methylpyrrole studied by gas electron diffraction using rotational constants and liquid–crystal NMR spectroscopy. J Mol Struct 2001. [DOI: 10.1016/s0022-2860(01)00538-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Korter TM, Pratt DW. Perturbations of the Fully Resolved Electronic Spectra of Large Molecules by the Internal Rotation of Attached Methyl Groups. Influence of Complex Formation. J Phys Chem B 2001. [DOI: 10.1021/jp004451h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Timothy M. Korter
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - David W. Pratt
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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Schafer M, Bauder A. Microwave spectra and structure of the fluorobenzene-carbon monoxide van der Waals complex. Mol Phys 2000. [DOI: 10.1080/00268970050032783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Bruhn T, Mäder H. The Microwave Spectrum of m-Tolunitrile: Methyl Internal Rotation and (14)N Nuclear Quadrupole Coupling. JOURNAL OF MOLECULAR SPECTROSCOPY 2000; 200:151-161. [PMID: 10708528 DOI: 10.1006/jmsp.1999.8043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The microwave spectrum of m-tolunitrile (3-methylbenzonitrile, m-C(6)H(4)CH(3)CN) has been investigated in the frequency range from 1 to 4 and 8 to 26.5 GHz. The spectra in the two lowest states of internal methyl rotation (m = 0, +/-1) were recorded by means of pulsed molecular beam Fourier transform microwave (MB-FTMW) spectrometers. The interpretation of the spectra was based on an asymmetric frame-symmetric top Hamiltonian with inclusion of centrifugal distortion terms and first-order contributions from (14)N nuclear quadrupole coupling. A least-squares analysis yielded the rotational constants A = 3295.9103(10) MHz, B = 1199.1188(2) MHz, C = 883.9223(1) MHz, all elements of the nuclear quadrupole coupling tensor chi(aa) = -3.626(1) MHz, chi(bb) = 1.684(1) MHz, chi(cc) = 1.943(1) MHz, and chi(ab) = -1.870(3) MHz, as well as the threefold barrier to internal rotation, V(3) = 14.2 cm(-1), and the angle between the internal rotor axis and the principal moment of inertia a axis, θ = 42.66 degrees, using fixed values for the sixfold barrier term V(6) (-11 cm(-1)) and the moment of inertia of the methyl top I(alpha) (3.16 u Å(2)). Copyright 2000 Academic Press.
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Affiliation(s)
- T Bruhn
- Institut für Physikalische Chemie, Universität Kiel, Olshausenstr. 40, Kiel, 24098, Germany
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HANSEN N, MÄDER H, BRUHN T. A molecular beam Fourier transform microwave study of0-tolunitrile:14N nuclear quadrupole coupling and methyl internal rotation effects. Mol Phys 1999. [DOI: 10.1080/00268979909482857] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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