Diethyl [4-(2,2':6',2''-terpyridine-4'-yl)phen-yl]phospho-nate.

The title compound, C25H24N3O3P, was obtained by catalytic phospho­nation of 4′-(4-bromphen­yl)-2,2′:6′,2′′-terpyridine. The terpyridine moiety is nearly planar, the dihedral angles between the central and the outer rings being 4.06 (9) and 5.39 (9)°. The N atoms in the two pyridine rings are oriented nearly anti­periplanar to that of the central ring. The benzene ring is rotated out of the plane of the central ring of the terpyridine unit by 34.65 (6)°.