New copper(II) complexes with sterically hindered oxamato ligand: synthesis, crystal structures, spectroscopic properties

Abstract

We report the synthesis, crystal structures and spectroscopic properties of two new copper (II) complexes of formula (NMe4)2 [Cu(bpea)2] (1) and (NBu4)2 [Cu(bpea)2]·2.5H2O (2) [bpea = N-2,2-diphenylethyloxamate]. Crystal structures of complexes 1 and 2 were solved in P-1 and P21/c space groups. Both complexes are mononuclear species where the bidentate oxamato ligands adopt a trans conformation and the Cu(II) is four-coordinated in a perfect square planar geometry. The EPR spectral parameters correspond to the gz = g//≫ gy = gx = g⊥and Az = A//≫ Ax = Ay = A⊥ relations which are characteristic of axial symmetry of coordination geometry of Cu(II) centers and d (x2-y2) ground state orbital of cooper (II) unpaired electron.