Iridates from the molecular side

New exotic phenomena have recently been discovered in oxides of paramagnetic Ir4+ ions, widely known as ‘iridates’. Their remarkable properties originate from concerted effects of the crystal field, magnetic interactions and strong spin-orbit coupling, characteristic of 5d metal ions. Despite numerous experimental reports, the electronic structure of these materials is still challenging to elucidate, and not attainable in the isolated, but chemically inaccessible, [IrO6]8– species (the simplest molecular analogue of the elementary {IrO6}8− fragment present in all iridates). Here, we introduce an alternative approach to circumvent this problem by substituting the oxide ions in [IrO6]8− by isoelectronic fluorides to form the fluorido-iridate: [IrF6]2−. This molecular species has the same electronic ground state as the {IrO6}8− fragment, and thus emerges as an ideal model for iridates. These results may open perspectives for using fluorido-iridates as building-blocks for electronic and magnetic quantum materials synthesized by soft chemistry routes.