A. Bencini, E. Berni, F. Chuburu
Jun 15, 2002
Citations
0
Influential Citations
4
Citations
Journal
Polyhedron
Abstract
Abstract The synthesis of the two new linear hexa-amines, 3,7,10,14-tetraazahexadecane-l,16-diamine (L 1 ) and 5,9,12,16-tetraazaicosane-l,20-diamine (L 2 ) has been reported. Ligand protonation and Cu(II) and Zn(II) coordination have been studied in aqueous solution by means of potentiometric, microcalorimetric (298.1 K, I =0.1 mol dm −3 ) and spectrophotometric (UV–Vis, 1 H and 13 C NMR) measurements. The species present in solution and their stability constants have been determined. L 1 forms mono- and binuclear complexes in aqueous solution with Cu(II). In the [ML 1 ] 2+ complexes, the metal ion is coordinated by five nitrogen atoms, while in the [ML 2 ] 2+ complexes the metal ion is four-coordinate. This different behavior is explained in terms of the different numbers of methylene groups between adjacent nitrogen atoms.