Template synthesis of copper(II)lead(II) complexes of new binucleating macrocycles with dissimilar co-ordination sites

Abstract

New binucleating macrocycles comprised of two molecules of 2,6-diformyl-4-methylphenol, a diamine (ethylenediamine or 1,3-propanediamine), and a diaminoalcohol (1,3-diaminopropan-2-ol or 1,5-diaminopentan-3-ol) have been synthesised as copper(II)lead(II) complexes by ‘stepwise’ template reactions. The macrocycles possess two dissimilar co-ordination sites, a four-co-ordination N₂O₂ donor set and a five-co-ordination N₂O₃ set, sharing two bridging phenolic oxygens. The CuPb complex of the macrocycle with ethylenediamine and 1,3-diaminopropan-2-ol as the amine components has been structurally characterized by single-crystal X-ray analysis. The Cu^II is bound to the four-co-ordination site and has a planar configuration. The Pb^II is bound to the five-co-ordination site and assumes a seven-co-ordinate geometry with a unidentate perchlorate ion and a dimethylformamide molecule. In the macrocycles derived from 1,3-diaminopropan-2-ol the alcoholic oxygen can co-ordinate to Pb^II in both protonated and deprotonated forms, whereas in the macrocycles derived from 1,5-diaminopentan-3-ol the alcoholic oxygen co-ordinates to Pb^II in only the deprotonated form. Template synthesis of the macrocycle of 1,3-propanediamine and 1,5-diaminopentan-3-ol, using Cu^II and Ba^II as template ions, afforded a mononuclear copper(II) complex in which the five-co-ordination site of the macrocycle is occupied by a proton instead of Ba^II.