Conformational Analysis. V. The Molecular Structure, Torsional Oscillations, and Conformational Equilibria of Gaseous 1,3-Dibromopropane, (CH2Br)2CH2, as Determined by Electron Diffraction and Compared with Semi-empirical (Molecular Mechanics) Calculations.

Farup, Per Erik; Stølevik, Reidar; Frederichsen, P. S.; Nakken, K. F.

doi:10.3891/acta.chem.scand.28a-0680

Cited by 41 publications

(10 citation statements)

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“…Because structural dynamics is a major part of this work, we will start by considering the four conformers of DBP shown in Figure . From electron diffraction studies it was determined that in a gas phase sample of DBP at 65 °C (a temperature close to our experimental conditions) there is 67% g,g- C 2 , 30% a,g- C 1 , and 3% a,a- C 2 v (the g,g- C s conformer was not present in detectable amounts), reflecting that there is a stabilizing interaction between the bromine atoms. In competition with steric hindrance.…”

Section: Resultssupporting

confidence: 51%

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

2011

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Section: Resultssupporting

confidence: 51%

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

2011

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“…The periodic signal persists under these conditions and is therefore due to vibrational coherence. 15,28 The ground-state DBP (C 2 symmetry) has only one vibration with a low frequency (∼50 cm -1 ) 14,19 with a period which is similar to that of the observed coherence (τ c ) 680 fs). This is the δ(CCCBr) torsion with "a" symmetry.…”

Section: B δ(Cccbr)supporting

confidence: 60%

“…According to these electron diffraction studies, the gauche-gauche conformation is the most stable for DBP, 1,3-diiodopropane, and 1-bromo-3-chloropropane. 19,20 Molecular mechanics calculations indicate that this is also the case for the other investigated 1,3-dihalocompunds. 21 Calculations were performed using the Gaussian 98 program package.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 55%

“…These are the anti−anti, anti−gauche and the gauche−gauche conformation, as shown in Figure . According to these electron diffraction studies, the gauche−gauche conformation is the most stable for DBP, 1,3-diiodopropane, and 1-bromo-3-chloropropane. , Molecular mechanics calculations indicate that this is also the case for the other investigated 1,3-dihalocompunds …”

Section: Experimental and Theoretical Methodsmentioning

confidence: 83%

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Coherent Dynamics in Complex Elimination Reactions: Experimental and Theoretical Femtochemistry of 1,3-Dibromopropane and Related Systems^,

et al. 2001

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Dynamics of the elimination reaction of 1,3-dibromopropane is studied here using femtosecond time-resolved mass spectrometry. It is shown that the complex reaction involving 27 internal degrees of freedom, which is initiated at a total energy of 186 kcal mol-1 (corresponding to a n → 5p Rydberg transition), can be described in a reduced space of two coordinates. The first coordinate is the coherent torsional motion involving the two C−Br bonds. The period was observed to be 680 fs. The second coordinate is the C−Br bond-breaking coordinate. The cleavage occurs in 2.5 ps and yields the 3-bromopropyl radical, which subsequently reacts (cleavage of the second C−Br bond and ring closure) to give cyclopropane in 7.5 ps. The reaction channels were identified with the aid of density functional theory calculations. Analyses of orbital populations, energies, and ionization potentials for the different conformations are entirely consistent with the observation of the oscillatory coherent motion and the phase shifts that are observed between certain transients. The interactions of the lone-pairs of the two bromine atoms are shown to be the key for changing the ionization characteristics along the torsional coordinate and thereby enabling the selective probing of vibrational coherence.

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“…The calculations performed show the GG form having the lowest energy, like in fluoroalkanes. The analysis of results obtained (Table 4) show that MP2/6-31G(3d1f , 3p) overestimates RCE values while HF/6-31G(d) results are in perfect agreement with [20]. Therefore one can conclude HF/6-31G(d) being sufficiently good for larger bromoalkanes.…”

Section: Estimation Of Additivity Increments Corresponding To the Seqsupporting

confidence: 67%

Additivity of conformational energy: Quantum mechanical investigation of fluoro- and bromoalkanes

Jankauskas¹

2007

Lithuanian J. Phys.

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The possibility to use additivity rule [1] for estimation of relative conformational energies of fluoro-and bromo-substituted alkanes is studied. The ability of quantum mechanical methods (HF and MP2) to estimate the additivity increments EThe obtained results have been compared with available experimental data. It is shown that increments are sensitive to the method and basis set used. The arrangement of relative conformational energies for various conformers in the series of polysubstituted fluoro-and bromoalkanes obtained using additivity rule agrees both with experimental findings and quantum mechanical calculations. The results lead to the conclusion that it is possible to work out the quantum mechanically based additivity schemes for investigated compounds.

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Conformational Analysis. V. The Molecular Structure, Torsional Oscillations, and Conformational Equilibria of Gaseous 1,3-Dibromopropane, (CH2Br)2CH2, as Determined by Electron Diffraction and Compared with Semi-empirical (Molecular Mechanics) Calculations.

Cited by 41 publications

References 0 publications

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

Coherent Dynamics in Complex Elimination Reactions: Experimental and Theoretical Femtochemistry of 1,3-Dibromopropane and Related Systems^,

Additivity of conformational energy: Quantum mechanical investigation of fluoro- and bromoalkanes

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Conformational Analysis. V. The Molecular Structure, Torsional Oscillations, and Conformational Equilibria of Gaseous 1,3-Dibromopropane, (CH2Br)2CH2, as Determined by Electron Diffraction and Compared with Semi-empirical (Molecular Mechanics) Calculations.

Cited by 41 publications

References 0 publications

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

Real-Time Probing of Structural Dynamics by Interaction between Chromophores

Coherent Dynamics in Complex Elimination Reactions: Experimental and Theoretical Femtochemistry of 1,3-Dibromopropane and Related Systems,

Additivity of conformational energy: Quantum mechanical investigation of fluoro- and bromoalkanes

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Coherent Dynamics in Complex Elimination Reactions: Experimental and Theoretical Femtochemistry of 1,3-Dibromopropane and Related Systems^,