Reactions of seven coordinate complexes. Synthesis, structure, and copper complex of the novel ligand 3-methyltriazolo(1,5-a)6-acetylsemicarbazonepyridine

The reaction of aquachloro(2,6-diacetylpyridinedisemicarbazone)copper(II) with hydrazine hydrate gave the copper complex of 3-methyltriazolo(1,5-a)6-acetylsemicarbazonepyridine. The free ligand was isolated from the copper complex. The X-ray structures of both the copper complex and the free ligand are reported. The copper complex and the free ligand both crystallize in the triclinic space group P1 with 2 molecules per cell. The Cu complex has cell dimensions of a = 8.8574(4), b = 10. 1764(5), c = 10.4434(5), alpha = 71.956(1) beta = 64.913(1), and gamma = 81.597(1)degrees. The Cu ion is in a square pyramidal arrangement, with the Cu, the ligand, and a Cl in the plane and a disordered Cl and HO in the apical position. The ligand has cell dimensions of a = 7.2696(7), b = 8.0516(7), c = 9.9326(9) Angstrom, alpha = 110.534(2), beta = 96.730(2), and gamma = 100.089(2)degrees. The ligand is planar with a conformation determined by an internal N-H...H hydrogen bond. The role of the Cu ion in the formation of the triazolopyridine is discussed. (C) 2003 Elsevier B.V. All rights reserved.