NEW HETEROMETALLIC DI-MU-HYDROXO CHROMIUM(III)-IRIDIUM(III) AND RHODIUM(III)-IRIDIUM(III) DINUCLEAR AQUA IONS

The synthesis and solution characterisation of bis(mu-hydroxo) heterom etallic chromium(III)-iridium(rn) and rhodium(III)-iridium(III) dinucl ear aqua ions, namely [(H2O)(4)Cr(mu-OH)(2)Ir(H2O)(4)](4+) and [(H2O)( 4)Rh(mu-OH)(2)Ir(H2O)(4)](4+) have been performed. Formation of such d inuclear ions is facilitated in alkaline media. Oxidation of the iridi um(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 cha racterisation included metal analyses, charge determination and UV/VIS absorption spectroscopy.