The Structural Effects of Substitution on the 1,3-Dioxolan-2-Ylium System

Abstract

<p> This thesis deals with 0-substituted carbenium ions. In particular, the relationship between the pattern of substitution and the nature of the charge distribution in the ion are probed by looking at the effects of systematic substituent change on bond distances.</p> <p> The model system employed in this investigation is the 1,3-dioxolan-2-ylium ion. A series of five ions were investigated by the preparation of single crystals which were studied using x-ray crystallography.</p> <p> The carbon oxygen bond distances around the five-membered dioxolanylium ring were found to be sensitive to changes in methyl substitution at position 4 of the ring. As methyl substitution at this position was increased systematically, an increase in the C4-03 carbon oxygen bond distance was observed.</p> <p> Changes in the substituent at position 2 of the dioxolanylium ring also had an effect on carbon oxygen bond distances but of a lesser magnitude than those brought about by methyl substitutions at position 4. The importance of these changes in structure are discussed in terms of the charge distribution in the cations.</p>