title: Shapes of benz[a]anthracenes: the crystal and molecular structure of 6-methylbenz[a]anthracene.
abstract: The crystal structure of 6-methylbenz[a]anthracene (6-MBA), a more potent carcinogen than the other K-region monomethyl-substituted benz[a]anthracene (5-MBA), has been determined by application of direct methods to single-crystal X-ray diffractometric data and refined by least squares to R = 0.047 (Rw = 0.053). Deviations of the carbon atoms from planarity are very small with even the methyl carbon displaced by only 0.05 A from the mean molecular plane. The benzo-ring A is inclined at only about 1 1/2 degrees to each of the three rings in the anthracene moiety, i.e. 6-MBA is one of the most nearly planar benz[a]anthracenes. The K-region bond C(5)-C(6) = 1.328(6) A and two other short bonds are C(8)-C(9) = 1.341(7) and C(10)-C(11) = 1.361(7) A in the anthracene D ring.
authors.affiliation: Department of Chemistry and Chemical Technology, University of Bradford, West Yorkshire, England.
authors.forename: D W
authors.initials: DW
authors.lastname: Jones
authors.forename: J D
authors.initials: JD
authors.lastname: Shaw
mesh_terms: D001551:Benz(a)Anthracenes; D015394:Molecular Structure; D014961:X-Ray Diffraction
chemical_list: D001551:Benz(a)Anthracenes; C046305:6-methylbenz(a)anthracene