Ab initio and density functional calculations of conformational energies and interconversion pathways in 1,2,3,6-tetrahydropyridine

作者：Tran Tung; Malloy Thomas B Jr^*

来源：Journal of Molecular Structure, 2010, 970(1-3): 66-74.

DOI：10.1016/j.molstruc.2010.02.035

• Conformations
• Barriers
• Interconversion

Hartree-Fock with and without MP2 (frozen core and full) corrections and density functional calculations have been performed on 1,2,3,6-tetrahydropyridine with basis sets 6-31G*, 6-31+G* and 6-311+G**. For all methods which included diffuse functions, the half-chair equatorial N-H conformer was found to be slightly more stable than the half-chair axial conformer, in agreement with experimental results. A detailed comparison for all the methods and basis sets was made with experimental data. These included rotational constants for both the normal and N-D isotopic species, dipole moments and dipole moment components. In addition, several interconversion pathways and barriers between the axial and equatorial conformations were explored by Hartree-Fock and B3LYP with the 6-31+G* basis set. The lowest energy pathway between was found to be via the N-H inversion (similar to 4-5 kcal/mol); via a bent (boat) axial form (similar to 6-7 kcal/mol) and finally via a bent (boat) equatorial form (similar to 7-8 kcal/mol). The planar form was found to be similar to 10 kcal/mol less stable than the two half-chair forms.

• 出版日期2010-4-30