Coordination abilities of l-glutamic acid γ-monohydroxamic acid towards copper(II) in the absence and presence of some aliphatic amines

Abstract Solution equilibrium studies on the Cu 2+ –(A)–(Glu-γ-ha) ternary systems ((A) = polyamine: ethylenediamine (en), diethylenetriamine (dien), N , N , N ′, N ″, N ″-pentamethyldiethylenetriamine (Me 5 dien); (Glu-γ-ha) =  l -glutamic-γ-hydroxamic acid) have been performed by pH-potentiometry, UV–Vis spectrophotometry and EPR methods. The obtained results suggest the formation of the heteroligand complexes with [Cu(A)(Glu-γ-ha)] + stoichiometry in all studied systems. Our spectroscopic results indicate the tetragonal geometry for the [Cu(en)(Glu-γ-ha)] + species in which Glu-γ-ha acts as a tridentate ligand, the geometry slightly deviated from square pyramidal for [Cu(dien)(Glu-γ-ha)] + and strongly deviated from square pyramidal towards trigonal bipyramidal for the [Cu(Me 5 dien)(Glu-γ-ha)] + species. In the two latter species Glu-γ-ha acts as a bidentate ligand. The coordination modes in these mixed-ligand complexes are discussed.