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

Sodium 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.