Microwave spectrum, dipole moment and internal rotation potential function of gauche-cyclopropanol

Macdonald, John N.; Norbury, D.; Sheridan, J.

doi:10.1039/f29787401365

Cited by 31 publications

(42 citation statements)

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“…The closest open-chain analog is di-

-butyl carbinol, which is however calculated to adopt as well an asymmetric conformation as a consequence of the steric repulsion between the bulky groups. Symmetric secondary alcohols with known tunneling splittings are 2-propanol [ 94 ], cyclohexanol [ 95 ] and cyclopropanol [ 96 ]. They feature experimental splittings at least an order of magnitude smaller, which correlate with calculated B3LYP-D3(BJ) barriers at least twice as high.…”

Section: Resultsmentioning

confidence: 99%

“…As an alternative, we solve the Schrödinger equation explicitly for a relaxed scan of the torsional potential. To validate the performance of the torsion 1D code in combination with the electronic B3LYP potential, we compare results with the experimental benchmarking data set for tunneling splittings for 27 symmetric alcohol species [ 20 , 87 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 ] compiled in Ref. [ 93 ].…”

Section: Resultsmentioning

confidence: 99%

“… Correlation between logarithmized experimental tunneling splittings [ 20 , 87 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 ] and calculated ones with the 1D torsion code based on electronic B3LYP-D3(BJ)/may-cc-pVTZ potentials for 27 isotopologs of 16 symmetric alcohols. The diagonal line represents perfect agreement.…”

Section: Figurementioning

confidence: 99%

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Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of Alpha-Fenchol

et al. 2021

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Rotational microwave jet spectroscopy studies of the monoterpenol α-fenchol have so far failed to identify its second most stable torsional conformer, despite computational predictions that it is only very slightly higher in energy than the global minimum. Vibrational FTIR and Raman jet spectroscopy investigations reveal unusually complex OH and OD stretching spectra compared to other alcohols. Via modeling of the torsional states, observed spectral splittings are explained by delocalization of the hydroxy hydrogen atom through quantum tunneling between the two non-equivalent but accidentally near-degenerate conformers separated by a low and narrow barrier. The energy differences between the torsional states are determined to be only 16(1) and 7(1) cm−1hc for the protiated and deuterated alcohol, respectively, which further shrink to 9(1) and 3(1) cm−1hc upon OH or OD stretch excitation. Comparisons are made with the more strongly asymmetric monoterpenols borneol and isopinocampheol as well as with the symmetric, rapidly tunneling propargyl alcohol. In addition, the third—in contrast localized—torsional conformer and the most stable dimer are assigned for α-fenchol, as well as the two most stable dimers for propargyl alcohol.

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“…The closest open-chain analog is di-

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

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Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of Alpha-Fenchol

et al. 2021

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“…The closest open-chain analog is di-tert-butyl carbinol, which is however calculated to adopt as well an asymmetric conformation as a consequence of the steric repulsion between the bulky groups. Symmetric secondary alcohols with known tunneling splittings are 2-propanol [86], cyclohexanol [87] and cyclopropanol [88]. They feature experimental splittings at least an order of magnitude smaller, which correlate with calculated B3LYP-D3(BJ) barriers at least twice as high.…”

Section: Theoretical Investigation Of Torsional States Of α-Fencholmentioning

confidence: 87%

Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of alpha-Fenchol

Medel¹,

Springborn²,

Crittenden³

et al. 2021

Preprint

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Rotational microwave jet spectroscopy studies of the monoterpenol α-fenchol have so far failed to identify its second expected torsional conformer, despite computational predictions that it is only very slightly higher in energy than the most stable conformer. Vibrational FTIR and Raman jet spectroscopy investigations reveal unusually complex OH and OD stretching spectra compared to other alcohols. Via modelling of the torsional states, observed spectral splittings are explained by delocalization of the hydroxy hydrogen atom through quantum tunneling between the two non-equivalent but accidentally near-degenerate conformers separated by a low and narrow barrier. The energy differences between the torsional states are determined to be only 16(1) and 7(1) cm$^{−1}hc$ for the protiated and deuterated alcohol, respectively, which further shrink to 9(1) and 3(1) cm$^{−1}hc$ upon OH or OD stretch excitation. Comparisons are made with the more strongly asymmetric monoterpenols borneol and isopinocampheol as well as with the symmetric, rapidly tunneling propargyl alcohol. Assigned are also for α-fenchol the third – in contrast localized – torsional conformer and the most stable dimer, as well as for propargyl alcohol the two most stable dimers.

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“…Usually this is the bisected form. One exception is cyclopropanol14 which occupies a synclinal conformation. The actual molecular symmetry of this molecule is therefore C 1 , and the two vicinal bonds differ in length (149.5 and 150.9 pm).…”

Section: Calculated Cc Bond Lengths [Pm] and Experimental Ionizationmentioning

confidence: 99%

Electronic and Geometrical Structures of Cyclopropanes: Linear Correlation of Ionization Energies with CC Bond Lengths in Monosubstituted Cyclopropanes

Rademacher

2003

ChemPhysChem

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The unique structure of the three-membered ring renders cyclopropane derivatives appropriate candidates for studies of substituent effects on molecular properties. The molecules are relatively small and can be treated adequately by suitable and comprehensible models.[1] It is well-known that substituents affect the geometry of the ring, [2±5] and qualitative models for the interplay between electronic and geometrical structures with different degrees of sophistication have been proposed (see below). However, quantitative models are still awaiting their elucidation. Recently, we have shown that in p-acceptor substituted cyclopropanes (eight compounds, R 0.962) [6] as well as in halogenocyclopropanes (12 compounds, R 0.928) [7] the difference Dr in the lengths of vicinal and distal bonds is linearly correlated with the energy difference DIP w of the Walsh orbitals w S and w A . The former parameter was calculated by using the density functional theory (DFT) [8] B3LYP method, [9] and the latter parameter was determined from ionization potentials (IPs) measured by photoelectron (PE) spectroscopy. For both series of compounds, the correlation coefficient R can be considered as highly satisfactory. Changes in the C À C bond lengths can thus be explained quantitatively by the energy split of two molecular orbitals (MOs). Herein, we will show that such a linear relationship is of almost general validity for cyclopropane derivatives and applies for most types of substituents.In Figure 1, some orbitals of the cyclopropyl group, which are relevant for an investigation of substituent effects on ring structure, [1, 10±13] are depicted. These are the three Walsh orbitals [16] J.

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Microwave spectrum, dipole moment and internal rotation potential function of gauche-cyclopropanol

Cited by 31 publications

References 1 publication

Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of Alpha-Fenchol

Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of Alpha-Fenchol

Hydrogen Delocalization in an Asymmetric Biomolecule: The Curious Case of alpha-Fenchol

Electronic and Geometrical Structures of Cyclopropanes: Linear Correlation of Ionization Energies with CC Bond Lengths in Monosubstituted Cyclopropanes

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