Decomposition of the lanthanide-containing sandwich-type polyoxometalates: Synthesis and characterization of new multi samarium-containing polyoxometalates

Reaction of the trilacunary [A-α-SiW9O34]10− ligand with Sm(III) in 0.1 M carbonate solution at 40 °C produces the sandwich-type polyoxometalate of [A-α-SiW9O34)2(H2OSm)3CO3]13− (1). The controlled decomposition of the sandwich-type polyoxometalate of 1 in aqueous solution yields a new family of rare earth metal substituted POM of the formula [(SiW10Sm2O38)4(W3O8(OH)4)(H2O)2)]26− (2). 2 is isolated as mixed potassium, sodium salt and characterized by means of elemental analysis, IR spectra and single crystal analysis. We also obtained 2 via the reaction of Sm(III) with [A-α-SiW9O34]10− in 1:1 stoichiometric ratio without carbonate solution. The structure of 2, consists of four SiW10O3710− units, each incorporating two Sm(III) ions to create four Keggin-like anions that are further tied together by three additional tungstate units to form a tetramer species C2 symmetry polyoxometalate.