Co-ordinating properties in aqueous solution of the oxygen atom in bis-2-aminoethyl ether

Abstract

The stability constants of the Ni^II, Cu^II, and Zn^II complexes with bis-2-aminoethyl ether (oden) have been determined at 25 °C in 0·5M-KNO₃ and the enthalpies of reaction determined calorimetrically under the same conditions. The results are compared with those for diethylenetriamine (den). In all the complexes investigated the co-ordination of the oxygen atom is achieved. The simple M^II(oden) complexes are less stable than the corresponding den complexes, and the determining factor in the destabilisation is a less favourable enthalpic contribution. Thus we might consider the co-ordination of the ether oxygen atom as an endothermic process. The results obtained for the hydroxo-species [Cu(OH)(oden)]⁺ and [Zn(OH)(oden)]⁺ are different from results previously obtained for similar species. Explanations are suggested.