Synthesis and supramolecular structures of iso- and heteropolymetallates assisted by organoamino phosphonium cations

Abstract

Polyoxometallate (POM) clusters represent an interesting choice of building blocks for the construction of inorganic–organic hybrid materials. The supramolecular aggregation of several iso- and heteropolymetallate anions in presence of various organoamino phosphonium cations is described. The phosphonium POM salts 4–8 were prepared by the reaction of [P(NHR)4]Cl {1 (R = cyclohexyl), 2 (R = iso-butyl) and 3 (R = iso-propyl)} with Na2MoO4·2H2O/Na2WO4·2H2O. The compound 9, [P(NHCy)4]3[AsMo12O40], was prepared in a three component reaction involving 1, Na2MoO4·2H2O and Na2HAsO4. Formation of the Keggin clusters in 7 and 8 was achieved by a facile P–N bond cleavage of 3 under the acidic conditions of the reaction. X-ray structure analyses of the title compounds show an interesting range of hydrogen bonded supramolecular structures with topologies resembling from 2D-sheets to 3D-networks.