(9H-Fluoren-9-yl)(phenyl)phosphinic acid

The crystal structure of the title compound, C19H15O2P, features pairs of molecules joined by O—H...O hydrogen bonds across crystallographic inversion centers. In addition, π–π interactions, with a centroid–centroid distance of 3.6273 (9) between the fluorene ring systems, connect the dimers into chains along [01-1]. The three rings make dihedral angles of 1.34 (9), 1.52 (10) and 1.51 (7)° with each other.