Anion mediated diversity in the nuclearity of nickel(II) complexes with a N2O donor Schiff base: Formation of a supra-molecular chain via Br⋯Br interactions

Two nickel(II) complexes, [Ni(L)2] (1) and [Ni2(μ1,1-N3)2(L)2(DMSO)2] (2) [where HL = 3-(methylamino)propyliminomethyl-4-bromophenol, a tridentate Schiff base], have been synthesized and characterized by elemental analysis, IR, UV–Vis and fluorescence spectroscopy and single-crystal X-ray diffraction studies. The deprotonated tridentate Schiff base occupies three coordination sites of nickel(II) in each of the complexes. In the absence of any secondary coordinating anions, the octahedral geometry of nickel(II) in complex 1 is completed by the coordination of a second molecule of the tridentate Schiff base. On the other hand, in complex 2, the fourth coordination site of nickel(II) is occupied by an azide. A symmetry related azide from a different molecule coordinates the fifth site of nickel(II), thereby forming a double end-on azide bridged centrosymmertric dimer. An oxygen from a DMSO molecule occupies the sixth coordination site of nickel(II) to complete its octahedral geometry. There are hydrogen bonding and C–H⋯π interactions within the dinuclear moiety of complex 2. A one-dimensional chain along the a axis is produced in complex 1 via a Br⋯Br interaction.

Graphical abstractTwo nickel(II) complexes were synthesised with a tridentate N2O donor Schiff base. Presence of azide in the reaction medium favored the formation of a double end-on azide bridged centrosymmetric dinuclear complex. In absence of azide, a bis-ligand complex was produced. Br⋯Br interaction created a one-dimensional supra-molecular chain in one of the complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide