Octahedral complexes of cobalt(III) and nickel(II) incorporating with unsymmetrical NNO-donor hydrazone ligand: Synthesis and structural aspects

Two new octahedral cobalt(III) and nickel(II) complexes, [CoL ₂]·ClO ₄ (1) and [NiL ₂]·H ₂O·NO ₃ (2) containing the potentially tridentate Schiff base like hydrazone ligand, N'-[1-(pyridin-2-yl)ethylidene]acetohydrazide (L) (1:1 condensation product of acetichydrazide and 2-acetylpyridine) were synthesized and characterized by spectral a well as thermal analysis and single crystalX-ray diffractometry. Structural investigation shows that in both complexes, the centralCo or Ni atom belongs into N ₄O ₂ coordination sphere, developed with theNNOdonor sets of two independently hydrazone units. The corresponding M-N(pyridine) bonds being significantly longer than the M-N(imino) bonds, Co1-N1 and Co1-N4 [1.934(3) and 1.926(3) Å] for 1 and Ni1-N1 and Ni1-N4 [2.076(3) and 2.085(3)Å] for 2,Co1-N2 and Co1-N5 [1.846(3) and 1.854(3) Å] for 1 andNi1-N2 and Ni1-N5 [2.001(3) and 1.972(3)Å] for 2 respectively.