2-{2-[4-(4-Fluorophenyl)piperazin-1-yl]-2-oxoethyl}-6-(morpholin-4-yl)-4-phenylpyridazin-3(2H)-one

In the title compound, C26H28FN5O3, the morpholine ring adopts a chair conformation. The piperazine ring is puckered [Q T = 0.5437 (15) Å, θ = 8.89 (15) and ϕ = 357.2 (11)°]. The 1,6-dihydropyridazine ring makes dihedral angles of 28.03 (7) and 77.46 (7)° with the phenyl and benzene rings, respectively. In the crystal, molecules are linked along the c axis by C—H⋯O interactions and are flattened parallel to the ac plane. C–H⋯π interactions also contribute to the stability of the structure.

In the title compound, C 26 H 28 FN 5 O 3 , the morpholine ring adopts a chair conformation. The piperazine ring is puckered [Q T = 0.5437 (15) Å , = 8.89 (15) and ' = 357.2 (11) ]. The 1,6-dihydropyridazine ring makes dihedral angles of 28.03 (7) and 77.46 (7) with the phenyl and benzene rings, respectively. In the crystal, molecules are linked along the c axis by C-HÁ Á ÁO interactions and are flattened parallel to the ac plane. C-HÁ Á Á interactions also contribute to the stability of the structure.

Comment
In recent years, the 3(2H)-pyridazinone system has aroused a great deal of attention due to its structural relationship to pyrazolone derivatives such as aminopyrine and dipyrone in view of the ring enlargement of pyrazolone to pyridazinone.
These drugs possess analgesic and anti-inflammatory activities although they have limitations for their clinical use due to serious side effects such as blood dyscrasias (Şüküroğlu et al., 2006;Brogden, 1986).
A series of 6-morpholino-4-aryl-3(2H)-pyridazinone alkanoic acids, their ester and amide derivatives were prepared and tested for their in vivo analgesic activity by using the p-benzoquinone-induced writhing test. The title compound, C 26 H 28 FN 5 O 3 , generally showed higher activity but caused gastric ulceration in the animals (Şüküroğlu et al., 2006).
Theoretical calculations were carried out using the semiempirical quantum-mechanical CNDO/2 (Complete Neglect of Differential Overlap) method (Pople and Beveridge, 1970). The spatial view of the single molecule calculated as closed-shell in a vacuum is shown in Fig. 3 with atomic labels. The calculated dipole moment of (I) is about 2.795 Debye. The HOMO and LUMO energy levels are -10.013 and 0.832 eV, respectively.
According to the theoretical CNDO/2 and experimental X-ray structural results, the values of the geometric parameters of (I) are almost comparable within the experimental error interval (Allen et al., 1987).
The 1,6-dihydropyridazine ring (N1/N2/C7-C10) forms dihedral angles of 2.24 and 60.48° with the C1-C6 phenyl and C21-C26 benzene rings, respectively. The dihedral angle between the phenyl and benzene rings is 62.62°. The orientations of the planes of the rings are however, slightly different in the CNDO/2 and X-ray results. That is, intermolecular interactions play an important role in determining the crystal state conformation of (I).
After stirring the reaction mixture at 273 K for 15 min, 0.011 mole of 4-(4-fluorophenyl)-piperazine derivative was added to this solution. The final mixture was stirred at room temperature for 24 h and evaporated to dryness and then acetone was supplementary materials sup-2 added. All undissolved salts were filtered off, the filtrate was evaporated to dryness and the residue was recrystallized from acetone-water (1:1) to yield 62%, [m.p.: 457 K].

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.93 and 0.97 Å, and U iso (H) = 1.2U eq (C). Fig. 1. View of the title molecule with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.