Critical tests in the theory and application of nonstatistical dynamics

• Main Author: Goldman, Lawrence Michael
• Published: Cardiff University 2010
• Subjects: 547; QD Chemistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584784

Chapter one provides an overview of nonstatistical dynamics and the methodology presented in this work to search for such effects. Chapters two and three discuss a singlet biradical which was specifically designed to search for nonstatistical effects in the ring opening of a cyclopropylmethyl radical. These effects could be seen experimentally by observing the reactivity of the biradical as a function of the pressure of the supercritical fluid solvent. While several syntheses were designed to synthesise the biradical precursor, they were ultimately unsuccessful. Computational study of the biradical system highlights the convenience and accuracy of density functional theory in studying singlet biradicals. Molecular dynamics carried out on the biradical system is then discussed. The molecular dynamics confirms that this biradical should be a useful systems to search for nonstatistical dynamics. Chapters four and five discuss cyclopentadiene. When cyclopentadiene is formed from bicyclo[2.1.0]pent-2-ene, it can undergo a [1.5] hydrogen shift. We proposed that this hydrogen shift shows evidence for nonstatistical dynamics. Molecular dynamics calculations at the density functional theory level showed that hydrogen shift breaks the expected symmetry of the system. This symmetry breaking is caused by normal mode coupling which is a hallmark of nonstatistical dynamics. We have proposed a mechanism for the transformation of bicyclo[2.1.0]pent-2-ene into cyclopentadiene that explains the oscillatory behaviour of the hydrogen shift which is able to break the symmetry. We have also proposed isotope-labelling experiments that can be used to confirm the existence of nonstatistical behaviour for the cyclopentadiene system.