title: (E)-3,3',4,4',7,7',8,8'-Octa-methyl-2H,2'H-1,1'-bi(cyclo-penta-[fg]acenaphthyl-enyl-idene)-2,2',5,5',6,6'-hexa-one dichloro-methane monosolvate.
abstract: The title compound, C(36)H(24)O(6)·CH(2)Cl(2), is a dimer of two essentially planar (r.m.s., deviations of fitted plane of 14 pyracene C atoms = 0.0539 and 0.0543 Å) tetra-cyclic pyracene frameworks (each with four methyl groups and three carbonyl groups on the peripheral carbon atoms) twisted along a central C=C bond with an angle of 50.78 (3)° at 90 K. There are notably long Csp(2)-Csp(2) bonds associated with the carbonyl groups, the longest being 1.601 (3) Å between two carbonyl C atoms. There are also intermolecular carbonyl⋯carbonyl interactions of both parallel and antiparallel types, with C⋯O distances in the range 3.041 (3) to 3.431 (2) Å. This compound is of inter-est with respect to the synthesis of fullerene fragments, such as corannulene and semibuckminsterfullerene derivatives (or 'buckybowls'), and is a side product of the previously reported oxidation reaction. Structural details, such as planarity analysis of fused rings, out-of-plane deviation of substituents, inter-molecular inter-actions, and longer than typical bond lengths, will be discussed as well as comparisons to structurally related compounds.
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803,  USA.
authors.forename: Gregory T
authors.initials: GT
authors.lastname: McCandless
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sygula
authors.forename: Peter W
authors.initials: PW
authors.lastname: Rabideau
authors.forename: Steven F
authors.initials: SF
authors.lastname: Watkins
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek