produces
the sandwich-type polyoxometalate of [A-a-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-a-SiW9O34]10 in 1:1 stoichiometric
ratio without carbonate solution. The structure of 2, consists of four SiW10O37
10 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.
