Unprecedented formation of binuclear copper(II) complex with a perylene derived ligand by the oxidative reaction

A new perylene-pendent tridentate ligand, N-(3-perylenylmethyl)-N,N-bis(2-pyridylmethyl)amine (perbpa) 1 and its Cu(II) complex, [Cu(perbpa)Cl2] (2) were prepared and structurally characterized by the X-ray diffraction method. In the packing structure of ligand 1, perylene groups were aggregated to form a π–π stacked layer of dimerized pelylene moieties similar to the packing of pristine perylene. This result suggests both that the π–π interactions among the perylene moieties predominate for the arrangement of perbpa molecules in the crystal and that this ligand is a good candidate for constructing electron conducting path. A complex 2 was prepared from the ligand 1 and a copper(II) chloride dehydrate. Complex 2 had a mononuclear and 5-coordinate distorted square pyramidal structure with a perbpa and two coordinated chloride ions. The chemical oxidation of 2 by iodine resulted in the unprecedented binuclear Cu(II) species, [Cu2(μ-Cl)2(perbpa)2](I3)2, 3·(I3)2. An X-ray crystal structure analysis of 3·(I3)2 revealed the binuclear structure bridged by the chloride ions. A temperature dependent magnetic susceptibility measurement of 3 showed a weak ferromagnetic exchange interaction with S = 1 ground state, g = 2.12 and J = +1.17 cm−1, based on H = −2JS1 · S2. The UV–Vis absorption and the EPR spectra of 3 showed that the perylene groups are not oxidized. These results indicate a couple of Cu(II) constructed S = 1 ground state with intermolecular ferromagnetic interaction. The electrochemical study suggested that the crystallization of 3·(I3)2 was initiated by the oxidation of the N,N-bis-(2-pyridylmethyl)amino (bpa) groups of 2 by I2.