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)Cl-2] (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 pi-pi stacked layer of dimerized pelylene moieties similar to the packing of pristine perylene. This result suggests both that the p-p 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, [Cu-2(mu-Cl)(2)(perbpa)(2)](I-3)(2), 3.(I-3)(2). An X-ray crystal structure analysis of 3.(I-3)(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 = -2JS(1) . S-2. 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 center dot(I3) 2 was initiated by the oxidation of the N,N-bis-(2-pyridylmethyl) amino (bpa) groups of 2 by I-2. (C) 2010 Elsevier B.V. All rights reserved.