10-Benzoylphenanthrene-8,9-dicarboxylic anhydride

The asymmetric unit of the title compound, C23H12O4, contains two nearly parallel independent molecules; the dihedral angles between the phenanthrene ring systems of the two molecules and between the benzene rings of the two molecules are 4.97 (9) and 8.1 (2)°, respectively. In each molecule, the benzene ring is nearly perpendicular to the phenanthrene ring system, with dihedral angles of 86.42 (19) and 86.68 (18)°. π–π stacking exists between the phenanthrene ring systems of the two independent molecules [centroid–centroid distance = 3.698 (2) Å]. Short intermolecular contacts [O...O = 2.86 (2) and C...O = 2.88 (2) Å] are also present in the crystal structure.