The CuL2X2 (L = 7-nitro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one, known as nitrazepam, X = Cl, Br) complexes were prepared and investigated by IR, ESR and magnetic susceptibility measurements. The IR spectra suggest that the Cu(II) ion is coordinated by two nitrogen and two halogen atoms; The powder ESR spectrum at room temperature of CUL2Br2 is quasiisotropic, while that of CuL2Cl2 is characteristic of an axial monomeric species with small rhombic distortions. The isotropic ESR spectra of these compounds in DMF and Py solutions suggest the presence of pseudo-tetrahedral monomeric species. Two different monomeric species were evidenced in Cu(II)-nitrazepam solutions adsorbed onto NaY zeolite. (C) 1997 Elsevier Science B.V.