8. The influence of cavity size on the properties of encapsulated rhodium(III) lons: long-lived metal-centred emission in a symmetric expanded cavity rhodium cage system Rodney J. Geue,Martin B. McDonnell,Albert W. H. Mau,Alan M. Sargeson,Anthony C. Willis J. Chem. Soc. Chem. Commun. 1994 667