Crystal and molecular structure and properties of the first characterized copper(II) one-dimensional polymer containing mepirizole [4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine]

Abstract

The crystal and molecular structure of the complex [Cu(mpym)(H₂O)(C₄O₄)]·2H₂O [mpym = mepirizole = 4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine] has been determined by X-ray methods. It crystallizes in the orthorhombic space group Pbcn, with Z= 8, a= 18.592(3), b= 14.723(2) and c= 13.755(3)Å, R= 0.053 and R′= 0.070 for 2697 reflections. The structure comprises infinite chains parallel to [001] built up of 1-bis(monodentate) squarate-O¹O³ C₄O₄ anions bridging [Cu(mpym)(H₂O)]²⁺ units. The copper(II) ions display distorted trigonal-bipyramidal geometry. Both electronic and ESR spectra are indicative of an essentially d_z² ground state for the Cu^II. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is discussed on the basis of the relative orientation of the co-ordination polyhedron around the metallic atom and the bridging ligand.