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The Rotational Barrier in Ethane: A Molecular Orbital Study
Laboratory of Pharmaceutical Chemistry, Faculty of Chemistry, Autonomous University of Yucatan, 41 No. 421 Col. Industrial, C.P. 97150, Merida, Yucatan, Mexico
Institute of Chemistry, National Autonomous University of Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510 Mexico D.F., Mexico
* Author to whom correspondence should be addressed.
Received: 27 March 2012; in revised form: 12 April 2012 / Accepted: 12 April 2012 / Published: 20 April 2012
Abstract: The energy change on each Occupied Molecular Orbital as a function of rotation about the C-C bond in ethane was studied using the B3LYP, mPWB95 functional and MP2 methods with different basis sets.Also, the effect of the ZPE on rotational barrier was analyzed. We have found that σ and π energies contribution stabilize a staggered conformation. The σs molecular orbital stabilizes the staggered conformation while the stabilizes the eclipsed conformation and destabilize the staggered conformation. The πz and molecular orbitals stabilize both the eclipsed and staggered conformations, which are destabilized by the πv and molecular orbitals. The results show that the method of calculation has the effect of changing the behavior of the energy change in each Occupied Molecular Orbital energy as a function of the angle of rotation about the C–C bond in ethane. Finally, we found that if the molecular orbital energy contribution is deleted from the rotational energy, an inversion in conformational preference occurs.
Keywords: staggered conformation; ethane; rotational barrier; molecular orbital; DFT
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Quijano-Quiñones, R.F.; Quesadas-Rojas, M.; Cuevas, G.; Mena-Rejón, G.J. The Rotational Barrier in Ethane: A Molecular Orbital Study. Molecules 2012, 17, 4661-4671.
Quijano-Quiñones RF, Quesadas-Rojas M, Cuevas G, Mena-Rejón GJ. The Rotational Barrier in Ethane: A Molecular Orbital Study. Molecules. 2012; 17(4):4661-4671.
Quijano-Quiñones, Ramiro F.; Quesadas-Rojas, Mariana; Cuevas, Gabriel; Mena-Rejón, Gonzalo J. 2012. "The Rotational Barrier in Ethane: A Molecular Orbital Study." Molecules 17, no. 4: 4661-4671.