Ionophoric binding of alkaline earth metal ions (M2+) by tris-(arylazo oximato)osmium(II) anions, [OsA3]−

Abstract

High-yield synthetic routes to trinuclear complexes of the type [M(OsA3)2] (M = Mg, Ca, Sr or Ba; A = anion of arylazo oxime) by reaction of NaEOsA 3] and M(C104) 1, or of [HOsA3] with MCO 3, are described. The new complexes have been characterized on the basis of spectroscopic and physico-chemical results. The alkaline earth metal ions are held in an 0 6 matrix of two facial I-OsA3] units, each behaving as a tridentate (O, O, O) ligand. Quantitative transport of one equivalent of M 2 + from the aqueous to the organic (CHzC12) phase can be achieved with two equivalents of [OsA3]-. When the aqueous phase is acidified with two tool of H+, [M(OsA3)e] decomposes into M 2+ and [HOsA3], and M 2+ returns to this phase in its free state.