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
作者:Isao Oonishi、Shigeru Ohshima、Shoji Fujisawa、Junji Aoki、Yuji Ohashi、Tadeusz Marek Krygowski
DOI:10.1016/0022-2860(92)80107-s
日期:1992.2
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
An improved synthetic method gives pure 7H-dibenz[a,kl]anthracen-7-one, C21H12O, in a higher yield than those reported so far. The crystal structure has been determined by X-ray analysis. The space group is Pn21a, with unit cell dimensions of a=23.325(5), b=14.149(3), c=3.986(1) Å, and Z=4. The structure was solved by the direct method and refined by the block-diagonal least-squares method to an R value of 0.044. The molecule is greatly distorted from the planar conformation because of an intramolecular steric repulsion between the hydrogen atoms.