ja983471i_si_002.pdf (1.17 MB)

The Structure of Hexabenzotriphenylene and the Problem of Overcrowded “D3h” Polycyclic Aromatic Compounds

Download (1.17 MB)
journal contribution
posted on 14.01.1999 by Lisa Barnett, Douglas M. Ho, Kim K. Baldridge, Robert A. Pascal
Hexabenzotriphenylene (1, dibenzo[f,j]phenanthro[9,10-s]picene) has been prepared in 5% yield by vacuum pyrolysis of phenanthrene-9,10-dicarboxylic anhydride, and its X-ray structure has been determined. Compound 1 is a strongly twisted, D3-symmetric molecular propeller, in contrast to other highly substituted triphenylenes (perfluoro- and perchlorotriphenylene) which adopt C2-symmetric conformations. Computational studies of these and other overcrowded, nominally D3h-symmetric, polycyclic aromatic compounds are reported, and the origins of their conformational preferences and the adequacy of various computational methods for treating these compounds are discussed.