ESR study of some Cu(II)-oxazepam complexes

The CuL2X2 (L = 7-chlor-1,3-dihydro-3-hydroxi-5-phenyl-2H-1,4-benzodiazepin -2-one, also known as oxazepam, X = Cl, Br) complexes were prepared and inv estigated by ESR (electron spin resonance) method. Powder ESR spectra of Cu L2X2 compounds at room temperature show the presence of monomeric species h aving an axial symmetry with a small rhombic distortion. In case of compoun ds with Cl there is a superposition of two nonequivalent mononuclear specie s, one with a d(x2-y2) ground state and another with a d(x2) ground state. In pyridine (Py) and dimethylformamide (DMF) solutions the monomeric specie s prevail. Two different monomeric species, one with pseudotetrahedral (T-d ) and the other with elongated tetrahedral-octahedral symmetry, were eviden ced in DMF solutions adsorbed on NaY zeolite. In Py-DMF solutions two monom eric species were also identified. Dimeric species appear in DMF and Py sol utions adsorbed on NaY zeolite through the coordination of two Cu(II) ions at the same keto-oxygen from one oxazepam molecule.