Copper(II) coordination polymer based on L-arginine as a supramolecular hybrid inorganic-organic material - synthesis, structural, spectroscopic and magnetic properties

Abstract

We report the synthesis and structural, spectroscopic and magnetic properties of new 1D coordination polymeric complex of the formulae {[Cu(µ−l−Arg)2]SO4⋅1.5H2O}n (1) that contains asymmetric µ − O,O’ carboxylic bridge linking distorted square-pyramidal [Cu(µ−l−Arg)2]2+ coordination units. In 1D the syn − anti − µ2 − η1:η1 zig-zag polymer conformation, the adjacent Cu(II) ions are distanced by 5.707 Å, and the subsequent Cu∙∙∙Cu proximity in 1D− coordination chain equals 6.978 Å. Detailed interpretation of IR and Raman spectra of l−arginine and 1 has been performed. The values of EPR parameters (gx=2.059, gy=2.075, gz=2.228) indicate nearly of axial local symmetry of Cu(II) coordination sphere (elongated square pyramidal geometry) and correspond to dx2−y2 orbital of unpaired electron ground state. The single broad band at 16200 cm–1, characteristic for d − d transition, is assigned to the dominant dublet-dublet 2B1g(dx2−y2)→2Eg(dyz≈dxz) transition. Magnetic susceptibility measurement has revealed ferromagnetic coupling between the Cu(II) ions within the 1D−coordination chain, while the intermolecular coupling is antiferromagnetic.