Synthesis and crystal structures of N,N'-bis(5-methylsalicylidene)ethane-1,2-diamine and its bromido-, phenolato-, and dicyanoamido-cobridged polymeric copper(II) complex

Abstract

A bis-Schiff base N,N'-bis(5-methylsalicylidene)ethane-1,2-diamine (H₂L) was prepared and characterized by elemental analysis, ¹H NMR and ¹³C NMR spectra, MS, and single crystal X-ray diffraction (CIF file CCDC no. 1022761 (H₂L)). Reaction of the Schiff base with copper bromide and sodium dicyanoamide in methanol gave a novel bromido-, phenolato-, and dicyanoamido-cobridged polymeric copper(II) complex, ({Cu₂LBr[N(CN)₂]}₂)_n (I). Structure of complex I was characterized by elemental analysis and single crystal X-ray diffraction (CIF file CCDC no. 1022762 (I)). The smallest repeat unit of complex I is a dicyanoamide bridged tetranuclear copper(II) complex moiety, {Cu₂LBr[N(CN)₂]}₂, in which there possesses a crystallographic inversion symmetry. The tetranuclear moieties are further linked through Br atoms, forming a zigzag chain. The chains are further linked by dicyanoamide ligands, forming a 2D network. One Cu atom in complex I is coordinated by two N and two O atoms of the Schiff base ligand and one Br atom, forming square pyramidal geometry. The other Cu atom is coordinated by two N atoms of the Schiff base ligand, two N atoms of dicyanoamide ligands, and one Br atom, forming square pyramidal geometry. The bromido-, phenolato-, and dicyanoamido-cobridged Cu···Cu distances are 4.823(2), 2.955(1), and 7.121(3) Å, respectively. The [Cu₂L] units are linked by the bridging groups, to form 2D chains along the xy plane.