title: Exceptionally pyramidalized olefins: A theoretical study of the cyclopropenyl fused tricycles Tricyclo
abstract: RHF, MP2, and TCSCF ab initio theory and B3LYP, B3PW91, and SVWN density functional theory were used to study the series of cyclopropenyl-fused tricycles 9-12. In each of 9-12, the cyclopropenyl double bond is exceptionally pyramidalized (butterfly angle psi approximately 41-50 degrees ) with both endo and exo bent isomers. In the norbornyl systems (9 and 10), the endo bent isomers are more stable than the exo bent isomers, whereas in the bicyclo[2. 2.2]octadiene 12 the reverse is true with the exo bent isomer being the low energy form. The activation barriers for the endo/exo interconversions are calculated to be relatively low (DeltaH() approximately 6-13 kcal/mol).
authors.affiliation: Centre for Molecular Architecture, Central Queensland University, Rockhampton, Queensland 4702, Australia.
authors.initials: RV
authors.lastname: Williams
authors.initials: ME
authors.lastname: Colvin
authors.initials: N
authors.lastname: Tran
authors.initials: RN
authors.lastname: Warrener
authors.initials: D
authors.lastname: Margetic