PHENANTHRENE-9-CARBOXYLIC ACID

The title compound, C15H10O2, crystallized in the centrosymmetric spac e group C2/c. Hydrogen bonding is of the cyclic dimer type about a cen ter of symmetry. The carboxyl H and O atoms are ordered. The phenanthr ene core is almost planar and the dihedral angle between the core plan e and the carboxyl group plane is only 1.8 (1)degrees. The bay H atoms , H4 and H5, lie close to the core plane and 2.02 (2) Angstrom from ea ch other; the refinement places them on opposite sides of the core pla ne, but this result has little statistical significance.