Jump to main content
Jump to site search


Isomerization barriers and resonance stabilization for the conrotatory and disrotatory isomerizations of nitrogen containing tricyclo moieties

Author affiliations

Abstract

The isomerizations of 3,4-diazatricyclo[4.1.0.02,7]hept-3-ene and 3,4-diazatricyclo[4.1.0.02,7]heptane to their corresponding products were studied by ab initio calculations. Structures were determined at the multiconfiguration self-consistent field level and energies calculated at the single state second-order MRMP level. The isomerization of 3,4-diazatricyclo[4.1.0.02,7]hept-3-ene occurs through four unique pathways with barriers of 36.1 and 37.9 kcal mol−1 for the allowed channels, while those for the forbidden channels were 44.3 and 56.5 kcal mol−1. The 12.2 kcal mol−1 disparity in the disrotatory barriers is explained through electron delocalization in the transition state. The 3,4-diazatricyclo[4.1.0.02,7]heptane structure has eight separate reaction channels for isomerization, and the allowed barriers ranged from 37.4–43.3 kcal mol−1 while the forbidden barriers ranged from 49.5–57.3 kcal mol−1. Resonance stabilization for two of the forbidden pathways results in a relative energy lowering. The energy difference in the four allowed barriers is due mainly to steric considerations. The isomerization of 3,4,5-triazatricyclo[4.1.0.02,7]hept-3-ene through the disrotatory channel was studied to help identify stabilization effects from π bond electrons and lone pair electrons: π bond electrons showed greater contribution for molecular stabilization than lone pair electrons.

Graphical abstract: Isomerization barriers and resonance stabilization for the conrotatory and disrotatory isomerizations of nitrogen containing tricyclo moieties

Back to tab navigation

Supplementary files

Publication details

The article was received on 09 Aug 2018, accepted on 01 Oct 2018 and first published on 02 Oct 2018


Article type: Paper
DOI: 10.1039/C8CP05091K
Citation: Phys. Chem. Chem. Phys., 2018, Advance Article
  •   Request permissions

    Isomerization barriers and resonance stabilization for the conrotatory and disrotatory isomerizations of nitrogen containing tricyclo moieties

    W. Yang, K. N. Poland and S. R. Davis, Phys. Chem. Chem. Phys., 2018, Advance Article , DOI: 10.1039/C8CP05091K

Search articles by author

Spotlight

Advertisements