Synthetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of the aminoguanizone of pyruvic acid

Copper(II) complexes of general empirical formula, CuX(Hagpa) · nH2O and Cu(agpa) · 2H2O (H2agpa = aminoguanizone of pyruvic acid, X = Cl−, Br−, NO 3 - , CH3COO−, 1 / 2 SO 4 2 - , n = 0, 1, 1.5, 2), have been synthesized and characterized by IR, EPR spectroscopy and X-ray crystallography. The IR spectra of the complexes showed the ONN coordination of the ligand to copper(II) ion. The crystal structures of H2agpa · H2O and complexes [Cu(Hagpa)Br] and [Cu2(Hagpa)2(H2O)2(SO4)] · DMSO showed an invariable conformation and coordination mode for the uninegatively charged tridentate ligand and revealed the formation of linear polymers in which bromide or sulfate anions bridge the copper(II) ions. The EPR spectra for complexes CuX(Hagpa) · nH2O are described by spin Hamiltonian for S = 1/2, without hyperfine structure. The g-tensor is symmetrical for Cu(agpa) · 2H2O, has tri-axial anisotropy for sulfate complexes, and exhibits axial symmetry for the other compounds investigated.