New heterometallic di-µ-hydroxo chromium(III)–iridium(III) and rhodium(III)–iridium(III) dinuclear aqua ions

Abstract

The synthesis and solution characterisation of bis(µ-hydroxo) heterometallic chromium(III)–iridium(III) and rhodium(III)–iridium(III) dinuclear aqua ions, namely [(H₂O)₄Cr(µ-OH)₂Ir(H₂O)₄]⁴⁺ and [(H₂O)₄Rh(µ-OH)₂Ir(H₂O)₄]⁴⁺ have been performed. Formation of such dinuclear ions is facilitated in alkaline media. Oxidation of the iridium(III) to iridium(IV) in basic solutions was avoided by working under oxygen-free conditions. Separation and purification of the dinuclear ions has been carried out by ion-exchange chromatography. Solution characterisation included metal analyses, charge determination and UV/VIS absorption spectroscopy.