Magnetic circular dichroism and absorption spectra of some d5 hexahalides

Abstract

We have measured the m.c.d. and absorption spectra of RuCl₆^3–, RuBr₆^3–, and Ru(NH₃)₆Cl₃ in solution at room temperature and IrCl₆^2– in a rigid polymer matrix at room temperature and 10 K. The results are analysed in terms of the well-established charge-transfer interpretation. The splittings observed in the ²T_2u band at room temperature and that found in ²T_1u(π) at low temperature are attributed to the combined effects of a low symmetry distortion and spin–orbit coupling. The m.c.d. of the first band in Ru(NH₃)₆³⁺ suggests that this is a transition to the ²T_1u(σ) state.