Cooperative and competitive effects of substituents at C1 and C4 on the barriers to ring inversion of 5,5-difluorobicyclo[2.1.0]pentanes. Academic Article uri icon


  • To identify the reasons for the very low barrier that has been measured for ring inversion of 1,4,5,5-tetrafluorobicyclo[2.1.0]pentane (deltaG(double dagger) = 6.8 +/- 0.2 kcal/mol), CASSCF and CASPT2 calculations have been performed on ring inversion in this and other bicyclo[2.1.0]pentanes. The results of the calculations show that a cooperative interaction between the geminal fluorines at C2 and the fluorines at C1 and C3 in the singlet cyclopentane-1,3-diyl transition structure (TS) contributes 3.7 kcal/mol to lowering the barrier to ring inversion in the tetrafluoro compound. In contrast, a competitive substituent effect in the TS for ring inversion of 1,4-dicyano-5,5-difluorobicyclo[2.1.0]pentane is predicted to raise the barrier height by 6.1 kcal/mol. The origin of these cooperative and competitive substituent effects is discussed.

published proceedings

  • J Org Chem

author list (cited authors)

  • Shelton, G. R., Hrovat, D. A., & Borden, W. T.

citation count

  • 9

complete list of authors

  • Shelton, G Robert||Hrovat, David A||Borden, Weston Thatcher

publication date

  • April 2006