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 with 2 molecules per cell. The Cu complex has cell dimensions of a=8.8574(4), b=10.1764(5), c=10.4434(5) Å, α=71.956(1), β=64.913(1), and γ=81.597(1)°. 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 H2O in the apical position. The ligand has cell dimensions of a=7.2696(7), b=8.0516(7), c=9.9326(9) Å, α=110.534(2), β=96.730(2), and γ=100.089(2)°. 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.