Synthesis, crystal structures and supramolecular architectures of square pyramidal Cu(II) complexes containing aromatic chelating N,N’-donor ligands

Abstract

Design of new metal complexes is an interesting field for development of new functional molecular-based materials. In this process by the usage of mixed functional ligands one can precisely tune the physical and chemical properties of those metal complexes. However, it is difficult to obtain the desired complex in many cases for factors like different coordination abilities of the ligands and the types of anions have a great influence on the structure. A series of five copper(II) complexes [Cu(Bipy) (5-TPC) 2(H2O)] (1), [Cu(Phen) (5-TPC) 2(H2O)] (2), [Cu(NO3) (4,7-Phen) (5-TPC) (H2O)].H2O (3), [Cu(Bipy) 2(5-TPC)]2.(ClO4)2 (4), and [Cu2(Bipy)4(H2PO4)] (5) (where Bipy = 2,2'-bipyridine, Phen = 1,10-phenanthroline, 4,7-Phen = 4,7-hydroxy-1,10-phenanthroline, 5-TPC = 5-chloro-2- thiophene carboxylate) has been synthesized and characterised using single crystal X-ray diffraction studies. In all the compounds, the N,N’ ligand coordinates in a bidentate chelating manner and the copper has a square pyramidal geometry. Complexes (1,2) are expected to be isostructural due to similarity of the N.N’-chelating ligands used, but due to the difference in supramolecular architectures no similar unit cells were observed. This is important in crystal engineering point of view. Complexes (1–4) possess the neutral mononuclear and complex (5) possesses a dinuclear entity. These entities are connected by intermolecular interactions like X∙∙∙π, H∙∙∙X, (X = Cl) generating supramolecular architectures.