Electronic structure of Cu(II) complexes with N,N '-disalicylidene-1,2-cyclohexanediamine and N,N '-disalicylidenetrimethylenediamine

The electronic absorption and X-ray photoelectron spectra of N,N'-disalicylidenetrimethylenediaminatocopper(II) ([Cu(saltn)]) and N,N'-disalicylidene-trans-1,2-cyclohexanediaminatocopper(II) ([Cu(salchx)]) were measured. From these results and from informations derived from MO calculations the electronic structure of the complexes was clarified. Each electronic absorption band which can be assigned to the pipi* or ML/LMCT transition of [Cu(saltn)] or [Cu(salchx)] observed in the wavelength region of 450-200 nm appears at the almost same frequency as the corresponding band of N,N'-disalicylidencethylenediaminatocopper(II) ([Cu(salen)]) in solution. The LLCT bands (the intramolecular CT band between two T-electronic systems separated by saturated hydrocarbon chains such as -(CH2)(n-)) also appear at nearly the same positions (ca. 245 nm) for [Cu(salchx)], [Cu(saltn)], and [Cu(salen)]. The locations of the dd transition and the intensity of the ML/LMCT transition of [Cu(saltn)] are significantly different from those of [Cu(salen)] and [Cu(salchx)]. These differences may arise from the strengths of the interaction between metal and ligand.