Tris(4-formylphenyl)phosphane oxide tetrahydrofuran hemisolvate

The title compound, C21H15O4P·0.5C4H8O, contains an ordered phosphane oxide in a general position and a tetra-hydro-furan solvent mol-ecule disordered about a twofold axis. All three aldehyde substituents are nearly coplanar with their attached benzene rings, with C-C-C-O torsion angles in the range 1.64 (17)-4.24 (19)°. All three have different conformations with respect to the P=O group, one syn, one anti, and one gauche. Two of the aldehyde substituents form inter-molecular C-H⋯O contacts.