Structural Link between Giant Molybdenum Oxide Based Ions and Derived Keggin Structure: Modular Assemblies Based on the [BW_(11)O_(39)]~(9-) Ion and Pentagonal {M'M_5} Units (M' = W; M = Mo,W)

摘要

Polyoxometalate (POM) chemistry represents a large growing area in inorganic chemistry, and the ongoing interest is driven mainly by their potential applications in (electro)-catalysis, medicine, biology, and nanochemistry, The properties of this class of molecular materials are intimately related to their structural architecture and composition. Thus, the possibility to design new architectures and thereby to increase the library of available topological structures is an important goal in today's chemical research. Actually, until the beginning of the 1990s, this wide class of compounds was dominated by a few structural archetypes, namely, the Linqvist, Keggin, and Dawson anions. From 1994, Muller has advanced the knowledge of polyoxometalate chemistry with numerous reports on unprecedented nanosized arrangements based on molybdenum oxide clusters. These topological structures are characterized by a striking pentagonal building unit (Mo(Mo5)}, which condenses with metallic cations to form either spheroidal capsules (keplerate) or wheel-shaped clusters. Very recently, a mixed metal {W_(72)Mo_(60)} keplerate anion was reported, made up of 12 tungsten pentagonal motifs {W(W5)} mutually connected by 30 {Mo2O4OOCCH3}~+ linkers. Until now, the pentagonal motifs were found only in such classes of nanosized molecular materials and never observed among the wide class of numerous heteropolyoxotungstates deriving from conventional Keggin or Dawson structural archetypes. Hence, the present work establishes the first link between both subclasses of POM compounds.