The magnetic properties of (IrX₆)^2- complexes

The theory of low-spin d⁵ octahedral complexes is re-examined, and it is found that excited states can contribute significantly to the magnetic properties of the ground state. Electron spin resonance experiments have been performed on (IrX₆)^2- complexes (X = F, Cl, Br), and analysis of the data using the more detailed theory shows that these complexes are much more covalent (in terms of the magnitude of the admixture parameter fπ) than had hitherto been supposed.