Conformation of condensed polycyclic aromatic hydrocarbons Part III. The molecular and crystal structure of tribenzo [ a,h,rst] phenanthra [1,2,10- cde] pentaphene: a simple analysis of the in-plane distortions due to overcrowding

Abstract

The crystal and molecular structure of tribenzo [ a,h,rst] phenanthra [1,2,10- cde] pentaphene was determined by X-ray diffraction with final agreement factor R=0.057 for 2842 reflections. The molecule is largely distorted from a planar structure owing to a steric repulsion between the overcrowded hydrogen atoms. The deviations of the atoms from the mean plane of the whole molecule range from −1.78 to 1.52 Å. The molecule has an approximate twofold axis perpendicular to the mean molecular plane and takes a saddle form. A simple analysis of the out-of-plane and in-plane distortions shows that the latter should not be neglected.