2-Acetylpyrydine-aminoguanidine Schiff base – Novel ligand salt and zinc(II) complex containing thiocyanate

A new salt of Schiff base of aminoguanidine and 2-acetylpyridine, and its zinc(II) complex were obtained and their physicochemical and structural properties studied. The reaction of an aqueous solution of the chloride ligand salt and NH4NCS resulted in formation of the dithiocyanate ligand salt, L?2HNCS, while the reaction of the obtained salt with zinc(II) acetate gave a neutral complex of the formula [ZnL(NCS)2]. In this complex, chelate ligand is coordinated in its neutral form, in a common tridentate NNN manner, via pyridine, azomethine and imino nitrogen atoms of the aminoguanidine fragment. This coordination mode results in formation of two strained five-membered metallocycles. Zinc(II) is situated in a distorted square-pyramidal environment of the tridentate ligand and one thiocyanate ion in the equatorial and the other thiocyanate ion in the apical position. The crystal structure of the ligand salt is stabilized by N?H?N and N?H?S interactions formed between the cationic and anionic species, while the three-dimensional crystal packing of the complex units is based on weak N?H?S interactions which involve the S acceptors from both NCS ligands.

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