Reactions of quinquedentate Schiff base ligands with Mn and Cuions afforded icosa- and hexadecanuclear mixed-metal clusters inwhich dinuclear CuII complexes trapped oxo-bridged [MnIII8MnIV4O12]and [MnIII6O6] cores, respectively. Maximum entropy methodanalysis for synchrotron X-ray diffraction data was used todetermine the oxidation states of the Mn ions.