Structural Analysis of Polymeric Copper(II)–Pyrazinamide Complexes Prepared from Two Different Copper(II) Salts

Abstract

In crystal engineering, the presence of different types of anion may alter the structure of transition metal complexes. Thus, the anions may also govern the properties of the metal complexes. Hereby we reported a structural analysis of polymeric copper(II)-pyrazinamide (pza) complexes prepared from copper(II) sulphate and copper(II) chloride. The complexes were crystallised using a bench-top technique with copper(II):pza molar ratio of 1:2 in a layered H2O-CH3OH solvent at room temperature. Single crystal XRD, ATR-IR and melting point apparatus were used to analyse the structure and characterise the complexes. Single crystal XRD analyses reveals that both complexes, [Cu( µ-pza)(SO4)(H2O)2]n (A) and [Cu(pza)2( µ-Cl)2]n (B) forms a 1D polymeric structure with different metal-ligand connectivity around the octahedral copper centre. The copper centres are also linked by different ligand, namely pyrazinamide in A and chloride in B. Thus, the Cu…Cu distances in both complexes are different, 6.719 Å in A and 3.658 Å in B. Unlike in A, the crystal structure of B has two unique copper centres. In addition, crystal structures of A and B were also compared to closely related copper(II)-pza complexes from published literature. As also observed in many metal complexes, crystal structures of copper(II)-pza complex were affected by the anion of the metal salts used in the reaction, in which the anion also involves in the crystal structures.