Supramolecular structures and properties models of macrocyclic polymer complexes

Abstract

Two novel supramolecular complexes of types [Ru(L)(H2L) Cl·OH2] and [Ru(HLn)Cl3] (where H 2L is a potential tetradentate ligand derived from hydrazine hydrate and diethyl malonate, and HLn is a potential bidentate ligand derived from coupling of allyl azo-β-diketone) have been synthesized and characterized by elemental analysis, conductance and magnetic measurements, followed by 1H NMR, to determine the effect of substituents on the intramolecular hydrogen bond. The electronic properties and models of the bonding of ligands and complexes were investigated by UV-Vis and IR spectroscopies. The first type of complex contains terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations. Therefore, the reactions of allyl-β-diketone complexes with malonic dihydrazide have also been studied, as these cause ring closure and formation of supramolecular macrocyclic ligand complexes. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory, and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for the polymer complexes C. The macrocyclic polymer complexes D are pentacoordinate, and a trigonal-bipyramidal environment (D3h) is suggested for the ruthenium(III) ion. The effect of the Hammett constant on the ligand field parameters is also discussed. © 2004 John Wiley & Sons, Ltd.