Crystal structure of 13-(2-methoxyphenyl)-3,4-dihydro-2H-indazolo[1,2-b]phthalazine- 1,6,11(13H)-trione

In the title compound, C22H18N2O4, the three fused rings of the pyrazolophthalazine moiety are coplanar (r.m.s. deviation = 0.027 angstrom). The cyclohexene ring fused to the pyrazolidine ring, so forming the indazolophthalazine unit, has a half-chair conformation. The benzene ring is almost normal to the mean plane of the pyrazolophthalazine moiety, with a dihedral angle of 87.21 (6)degrees between their planes. In the crystal, molecules are linked by pairs of C-H center dot center dot center dot O hydrogen bonds forming inversion dimers. The dimers are linked via C-H center dot center dot center dot pi interactions, forming slabs parallel to (100). Between the slabs there are weak pi-pi interactions [ shortest inter-centroid distance = 3.6664 (9) angstrom], leading to the formation of a three-dimensional structure.