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

• Published in: Inorganica Chimica Acta 2008, Vol.361 (1), p.309-316
• Main Authors: Turta, Constantin I., Chapurina, Liudmila F., Donica, Ioana G., Voronkova, Violeta, Healey, Elisabeth R., Kravtsov, Victor Ch
• Format: Article
• Language: English
• Subjects: Aminoguanizone of pyruvic acid; Coordination polymers; Copper(II) complexes; EPR spectroscopy; X-ray crystallography
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2007.07.017

A series of coordination compounds of aminoguanizone of pyruvic acid with copper(II) have been studied by IR, EPR, and X-ray methods and revealed an invariable conformation and NNO chelate coordination mode of the uninegatively charged ligand. Linear coordination polymers in which bromide or sulfate anion bridges the copper(II) ions were found in the structure of two complexes. Copper(II) complexes of general empirical formula, CuX(Hagpa) · nH 2O and Cu(agpa) · 2H 2O (H 2agpa = aminoguanizone of pyruvic acid, X = Cl −, Br −, NO 3 - , CH 3COO −, 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 H 2agpa · H 2O and complexes [Cu(Hagpa)Br] and [Cu 2(Hagpa) 2(H 2O) 2(SO 4)] · 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) · nH 2O are described by spin Hamiltonian for S = 1/2, without hyperfine structure. The g-tensor is symmetrical for Cu(agpa) · 2H 2O, has tri-axial anisotropy for sulfate complexes, and exhibits axial symmetry for the other compounds investigated.