Structural and Coordinative Variability in Zinc(II), Cadmium(II), and Mercury(II) Complexes of 2‐Pyridineformamide 3‐Hexamethyleneiminylthiosemicarbazone

Abstract

AbstractSodium in dry methanol reduces 2‐cyanopyridine in the presence of 3‐hexamethyleneiminylthiosemicarbazide and produces 2‐pyridineformamide 3‐hexamethyleneiminylthiosemicarbazone, HAmhexim (1). Complexes with zinc(II), cadmium(II) and mercury(II) have been prepared and characterized by spectroscopic techniques. In addition, the crystal structures of HAmhexim (1), [Zn(Amhexim)(OAc)]2μ·μDMSO (2), [Cd(HAmhexim)Cl2]μ·μDMSO (7), [Cd(Amhexim)2] (8), [Cd(HAmhexim)Br2]μ·μDMSO (9), [Cd(HAmhexim)I2]μ·μEtOH (10), [Hg(HAmhexim)Cl2]μ·μDMSO (11), [Hg(Amhexim)Br]2 (13), [Hg3(HAmhexim)(Amhexim)Br5]μ·μH2O (14) and [Hg(Amhexim)I]2 (15) have been determined. Coordination of the anionic and neutral thiosemicarbazone ligand occurs through the pyridine nitrogen atom, imine nitrogen atom, and thiolato or thione sulfur atom. In [Zn(Amhexim)(OAc)]2 one of the bridging acetato ligands has monodentate coordination and the other bridges in a bidentate manner. [Cd(Amhexim)2] is a 6‐coordinate species while the other cadmium complexes are 5‐coordinate. In [Hg(Amhexim)Br]2 and [Hg(Amhexim)I]2 the thiolato sulfur atoms act as bridges between the Hg atoms to form dimeric compounds and [Hg3(HAmhexim)(Amhexim)Br5]μ·μH2O is a trinuclear complex with three different centers — two metallic centers have a 5‐coordination and the another one has 4‐coordination. In addition, [Hg(HAmhexim)Cl2]μ·μDMSO and [Hg3(HAmhexim)(Amhexim)Br5]μ·μH2O shown a supramolecular one‐dimensional hydrogen‐bonded self‐assembling.