4-[(4-Hydroxy-3-methoxybenzylidene)amino]-1,5-dimethyl-2-phenylpyrazolidin-3-one

The central system (N1/N2/C7/O1/C11/C9/C10/N3/C8) is planar, with an r.m.s. deviation of fitted atoms of 0.041 Å, and the dihedral angle with the phenyl ring (C1–C6) is 53.48 (8) . The vanillin moiety (C12–C15/C17–C19/O2/O3/C16) is planar, with an r.m.s. deviation of fitted atoms of 0.023 Å; the dihedral angle between the central system and the vanillin moiety is 12.12 (7) . Intermolecular hydrogen bonds (O2—H2 O1) are observed (Table 1), which stabilize the crystal structure. The molecules associate in a zigzag pattern via intermolecular hydrogen bonds to form a supramolecular structure. Received 16 May 2005 Accepted 23 June 2005 Online 30 June 2005