Nitrato-complexes of iridium. Part I. Ir3O(NO3)10

The new oxide nitrate of iridium(IV), Ir3O(NO3)10, is prepared from dinitrogen pentoxide and iridium tribromide. The i.r. spectrum suggests its formulation as [Ir3O(NO3)9]+NO3– its electronic spectra, X-ray powder pattern, room temperature magnetic moment, and chemical properties are discussed. A trinuclear structure involving pairs of nitrate bridges between octahedrally co-ordinated iridium atoms is suggested for the cation [Ir3O(NO3)9]+. The reaction between iridium tribromide and 100% nitric acid has also been studied.