1,5-Bis(4-chlorophenyl)-3-(2-oxo-1,2-dihydroquinolin-3-yl)pentane-1,5-dione, (Ia), and 1,5-bis(2-chlorophenyl)-3-(2-oxo-1,2-dihydroquinolin-3-yl)pentane-1,5-dione, (Ib), crystallize as an 84:16 mixture, 0.84C(26)H(19)Cl(2)NO(3)·0.16C(26)H(19)Cl(2)NO(3), in the space group I4(1)/a, where the molecules of the two isomers occupy very similar sites in the unit cell. A combination of one N-H...O hydrogen bond and one C-H...O hydrogen bond links the molecules, regardless of isomeric form, into a single three-dimensional framework structure. The molecules of (9RS,10RS)-8,9-bis(4-chlorobenzyl)-10-(2-oxo-1,2-dihydroquinolin-3-yl)-5,6,9,10-tetrahydrophenanthridine, C(36)H(22)Cl(2)N(2)O(4), (II), are linked by two hydrogen bonds, one each of the N-H...O and C-H...O types, into a molecular ribbon in which centrosymmetric rings of R(2)(2)(18) and R(4)(4)(24) types alternate. The hydrogen-bonded ribbons enclose channels, which contain highly disordered solvent molecules.