Theoretical and experimental studies of reactive organic molecules

Chapter I. Density functional theory calculations were used to examine the interconversions of C5H6 and C 6H8 isomers. On the C5H6 surface, cyclobutenylcarbene is predicted to rearrange to 1,2-cyclopentadiene. Interconversion of cyclobutylidenecarbene and cyclopentyne has a small barrier. For the C6H8 surface, cyclopentenylcarbene is predicted to rearrange to bicyclo[3.1.0]hex-5-ene and further to 1,3-cyclohexadiene. Cyclopentylidenecarbene can easily interconvert with cyclohexyne. These results are in accord with experimental results, to date. Carbene precursors via a cyclopropanated phenanthrene, 1,1-dihalo-1a,9b-dihydro-1H-cyclopropa[I]phenanthrene, were studied. Chapter II. Isodesmic and homodesmic equations at B3LYP/6-311+G(d,p) level of theory have been used to estimate strain for the series of cyclic allenes and cyclic butatrienes. A fragment strain approach was also developed and provides more accurate predictions for the larger rings. The strain estimations are in agreement with experimental results for these cumulenes. Chapter III. We have mapped the energy surface for the ozone + ketone reaction with B3LYP, BH&HLYP, CCSD(T) and CBS-QB3 methods. Oxidation by ozone renders aldehydes unsuitable for examining the tetroxolane hypothesis. (Abstract shortened by UMI.)