[Mn13O8(OEt)(6)(O(2)CPh)(12)] was prepared and its X-ray structure has been determined. It is the largest cluster in which there are three oxidation states of a given metal ion in one molecule. The core of the complex is a supercubane [(MnMn6Mn6II)-Mn-IV-Mn-III(mu(5)-O)(6)(mu(3)-O)(2)(mu(3)-OEt)(6)](12+). The magnetochemistry of the compound shows that only weak antiferromagnetic exchange interactions are present, and the ground state has S-T =(15)/(2) Six novel mu(5)-oxide ions support the frame of Mn the supercubane.