Octahedral Complexes of Cobalt(III) and Nickel(II) Incorporating with Unsymmetrical NNO-Donor Hydrazone Ligand: Synthesis and Structural Aspects

Abstract

Two new octahedral cobalt(III) and nickel(II) complexes, [CoL2]·ClO4 (1) and [NiL2]·H2O·NO3 (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 crystal X-ray diffractometry. Structural investigation shows that in both complexes, the central Co or Ni atom belongs into N4O2 coordination sphere, developed with the NNO donor 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) A] for 1 and Ni1–N1 and Ni1–N4 [2.076(3) and 2.085(3) A] for 2, Co1–N2 and Co1–N5 [1.846(3) and 1.854(3) A] for 1 and Ni1–N2 and Ni1–N5 [2.001(3) and 1.972(3) A] for 2 respectively. Two new octahedral cobalt(III) and nickel(II) complexes containing the potentially tridentate hydrazone ligand, N’-[1-(pyridin-2-yl)ethylidene]acetohydrazide (L) were synthesized and characterized by IR and UV–Vis spectra as well as thermal analysis and single crystal X-ray diffractometry.