1,1'-(Ethane-1,2-di-yl)bis-(indoline-2,3-dione).

The mol-ecule of the title compound, C(18)H(12)N(2)O(4), is situated on a crystallographic centre of symmetry. The mol-ecule has a zigzag structure, with two parallel symmetry-related indoline-2,3-dione fragments linked by an ethyl-ene group at each N atom. In the crystal, the mol-ecules stack in columns along the b axis. There are two such columns in the structure. The mol-ecules within each column are parallel; however, the mol-ecules in the two columns differ in the respective orientation of the indoline-2,3-dione fragments. In one column, they are approximately parallel to (112), while in the other they are approximately parallel to (12). The inter-planar angle between the indoline-2,3-dione fragments in the two columns is 80.83 (3)°. The mol-ecules within each column are related by mutual displacement of their centres of symmetry, that is (0, ±1/2, ±1/2). The packing between the mol-ecules is provided by weak inter-actions only, viz. C-H⋯O hydrogen bonds and π-π [centroid-centroid distance = 3.8745 (8) Å] and C=O⋯π inter-actions.