organic compounds
Open access
In the title phosphonate, C19H21O9P, the dihedral angle between the benzene rings is 63.33 (3)°, and the P atom has a distorted tetrahedral geometry, with angles in the range 101.30 (6)–120.38 (6)°. No significant intermolecular interactions are observed in the crystal structure, and π–π interactions between symmetry-related benzene rings are beyond 4 Å.