Insights into the Self-Assembly Mechanism of the Modular Polyoxometalate “Keggin-Net” Family of Framework Materials and Their Electronic Properties

The mechanism for the syntheses of inorganic framework materials based solely on polyoxometalate Keggin clusters has been examined and their electronic properties have been investigated. The assembly of the modular network compounds with the molecular formula (C4H10NO)n[W72M12O268X7] (with the heteroatom X = Si or Ge and the heterometal M = Co(II) or Mn(III)) is based on the isomerization of the metastable precursor material [γ-XW10O36]8–, followed by the inclusion of the heterometal and subsequent assembly into the extended framework structure. The two frameworks featuring manganese substitution can be dis- and reassembled in a recrystallization process while the cobalt versions do not show comparable behavior. The intrinsic differences of the four compounds with regards to their heteroatom and heterometal substitution are shown in terms of their redox behavior.