Molecular structure of 5,10-dimethoxybenzo[j]fluoranthene.

The molecular and crystal structure of the synthetic 5,10-dimethoxy derivative of the carcinogen benzo[j]fluoranthene has been determined by direct methods from X-ray diffractometric data and refined to an R index 0.041 over 2788 independent reflections. The benzo ring is inclined at approximately 3 degrees to the almost planar fluoranthene moiety (carbon atoms have r.m.s. deviation of 0.02 A from the carbon-atom plane); the methoxy carbon atoms lie within 0.2 A of the molecular plane. Corresponding bond lengths (e.s.d. 0.004 A for carbon-oxygen and carbon-carbon) and angles lie within 3 sigma for the two independent molecules, with mean dimensions of methoxy groups: C-C = 1.422, C-O = 1.372 A, C-O-C = 117.4 degrees.