6,7-Dihydro-3H-1,4-diazepino[1,2,3,4-lmn][1,10]phenanthroline-3,9(5H)-dione

In the title compound, C(15)H(12)N(2)O(2), the seven-membered ring bearing the three methyl­ene C atoms displays a puckered conformation, with the methyl­ene C atoms deviating from the plane of the benzene ring by 0.05 (1), 0.98 (1) and 1.04 (1) Å. The phenanthroline unit is not planar; the dihedral angles between this benzene ring and the other pyridyl rings are 9.62 (4) and 9.31 (4)°. The crystal packing is stabilized by π–π inter­actions between two phenanthroline ring systems, forming a centrosymmetric dimer with a centroid–centroid distance of 3.656 (1) Å.