The magnetic circular dichroism (MCD) of IrCl62minus;doped into crystalline (CH3NH3)2SnCl6has been studied from liquid helium to room temperature over the spectral region 6000ndash;3000 Aring;. The results confirm the new assignment (based on solution MCD data) wihch places the2T1uchargehyphen;transfer state at lower energy than the corresponding2T2ustate. The spinndash;orbit splitting of the2T2ustate which is not apparent in the absorption spectrum or solution MCD shows up strikingly in the crystal MCD illustrating the potentialities of such studies, particularly at low temperatures. The approximate1thinsp;sol;thinsp;Tvariation in the MCD from room temperature to 6deg;K shows conclusively that the allowed chargehyphen;transfer bands in MCD arise primarily fromCterms and is the first experimental demonstration over a very wide range of temperature of this theoretically expected temperature dependence. There is no indication of antiferromagnetic coupling, at least down to 6deg;K.
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