The bay-region geometry of some 5-methylchrysenes: Steric effects in 5,6- and 5,12-dimethylchrysenes

David E. Zacharias, Setsuo Kashino, Jenny P. Glusker, Ronald G. Harvey, Shantu Amin, Stephen S. Hecht

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The presence of a bay-region methyl group in carcinogenic polycyclic aromatic hydrocarbons leads to considerable distortion in the molecule. This is illustrated In the structures, obtained by X-ray diffraction techniques, of 5,12- and 5,6-dimethylchrysene. The molecular distortions result from steric requirements, such as that the minimum H{combining triple dot above}H distance is 1.8 Å and the minimum C{combining triple dot above}C distance is 2.90 Å; distortions to accommodate these requirements may be both in-plane (by increasing the angles at carbon atoms in the bay-region from 120° to ̃ 124°) and out-of-plane by torsion about certain bonds in the bay-region. It Is shown that more in-plane distortions are found for 5-methylchrysene derivatives than for methylbenz[a]anthracene derivatives and this, it is suggested, results from the nature of the flexibility of the chrysene compared with the benz[a]anthracene fragment at the bay-region.

Original languageEnglish (US)
Pages (from-to)1421-1430
Number of pages10
Issue number11
StatePublished - Nov 1984

Bibliographical note

Funding Information:
This work was supported by grants BC-132 and BC-242 from the American Cancer Society, CA-10925, CA-27780, CA-06927, CA-32242, CA-36097 and RR-05539 from the National Institutes of Health, and by an appropriation from the Commonwealth of Pennsylvania. One of the authors (S.K.) thanks the Japanese Ministry of Education for financial support, and Professor Masao Haisa for his encouragement.


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