Co (II), Ni(II) and Cu(II) complexes with a new pendant armed macrocyclic ligand showing several pi,pi-interactions

摘要

A new ligand, L, bearing four cyanoethyl pendant groups has been synthesized by reaction of the precursor ligand L-1 with acrylonitrile. The X-ray crystal structure of ligand L reveals the presence of a nanotubular structure in the solid state connected by intermolecular pi,pi-stacking interactions between adjacent pyridine rings. The coordination capability towards transition metal ions [Co(II), Ni(II) and Cu(II)] has been investigated starting from the hydrated nitrate and perchlorate salts of the metals. The new ligand L and the metal complexes obtained were characterized by elemental analysis, FAB MS, conductivity measurements, magnetic studies, IR and UV-vis spectroscopy. Furthermore, the crystal structure of ligand L and of the complexes [CoL][Co (NO3)(4)] center dot CH3CN (1), [NiL](NO3)(2) (3), [NiL](ClO4)(2) center dot CH3CN center dot 3H(2)O (4), [CuL][Cu(NO3)(3)(H2O)(2)](NO3) center dot H2O (5) and [CuL] (ClO4)(2) center dot 2CH(3)CN (6) were determined. The nitrate ions in the complexes are located near the pyridine rings and pi,pi-stacking interactions between pyridine rings, nitrate ions and nitrile groups have been found. (c) 2005 Elsevier B.V. All rights reserved.