Synthesis, crystal structure and characterization of a new mixed ligand cationic–anionic nickel(II) complex containing 1,4-diazepane

A new mixed ligand cationic–anionic nickel(II) complex, [NiL2][Ni(NCS)4(H2O)2] (1), where L = 1,4-diazepane has been synthesized by reacting nickel perchlorate with 1,4-diazepane and ammonium thiocyanate in the 1:1:2 M ratio. The complex has been characterized by elemental analysis, IR spectroscopy, TGA and single crystal X-ray diffraction studies. Structural studies reveal the presence of two independent mononuclear complex ions in 1 viz., a square planar [NiL2]2+ and an octahedral [Ni(NCS)4(H2O)2]2− which are held together by H-bonding to form a 3D supramolecular structure in the solid state.