Structural studies of polycyclic compounds and calixarenes

Abstract

In this dissertation, the molecular and crystal structures of several compounds containing polycyclic moieties of $D\sb3$-trishomocubane (pentacyclo (6.3.0$\sp{2,6}$.0$\sp{3,10}$.0$\sp{5.9}$) undecane) and its isomer - pentacyclo (5.4.0$\sp{2,6}$.0$\sp{3,10}$.0$\sp{5,9}$) undecane are reported. The results of structural studies on a pair of tetracyclic compounds: an alcohol and a ketone, as well as a precursor of a molecular cleft host are also presented. The geometrical features of the compounds were compared with those of the parent hydrocarbons (obtained from theoretical calculations) as well as those of related structures (from the Cambridge Structural Database). The factors responsible for bond elongation observed in the pentacyclo (5.4.0$\sp{2,6}$.0$\sp{3,10}$.0$\sp{5,9}$) undecane derivatives were studied using ab initio and semiempirical methods as well as molecular mechanics. The results eliminate "through bond" interaction between substituents as a possible cause of the observed geometrical abnormalities. In the second part of the dissertation the results of structural analyses of a series of four mercaptocalix (4) arenes are reported. The observed structural differences are explained in terms of the differences between chemical properties of thionyl and hydroxyl groups. The structure of a recently synthesized calix (5) arene exhibiting unusual "squashed" cone conformation is also presented. The results of conformational studies using cluster analysis on over 100 calix (4) arene structures from the Cambridge Structural Database are given.