[MnIIIMnIV2Mo14O56]17-: A Mixed-Valence Meso-Polyoxometalate Anion Encapsulated by a 64-Nuclearity Silver Cluster

A 64-nuclearity silver cluster encapsulating a unique POM anion [(MnMn2Mo14O56)-Mn-III-Mo-IV](17-) has been synthesized. The formation of the templating core performs a reassembly process for increasing nuclearities from {MnMo9} to {Mn3Mo14}. It represents a rare inorganic meso anion containing mixed-valent Mn that is built up by D-{(MnMo7)-Mo-IV} and L-{(MnMo7)-Mo-IV} units connecting together through a {Mn-III} fragment.