Abstract
A sandwiched-type carbonate-encapsulated yttrium-containing arsenotungstate(III) has been synthesized under mild reaction conditions. The polyanion [NaCH3COO{Y-2(H2O)(3)(B-alpha-AsW9O33)(2)(W2O5)(CO3)}](12-) (1) was isolated as a solid crystalline material by the reaction of a Y-III salt with the sodium salt of trilacunary [AsW9O33](9-) in sodium acetate solution. The sodium salt of the polyanion, i.e. Na-12[Na(CH3COO){Y-2(AsW9O33)(2)(W2O5)(CO3)(H3O)(3)}]center dot 22H(2)O (1a), was characterized by various analytical techniques, such as FT-IR, singlecrystal X- ray diffraction (SC-XRD), TGA (thermogravimetric analysis), C-13 NMR and ESI-MS (electrospray ionization mass spectrometry). SC-XRD studies revealed that the polyanion crystallizes in the triclinic space group P (1) over bar. The structure showed that the polyanion is a carbonate-encapsulated sandwichtype species, consisting of two trilacunary B-alpha-[AsW9O33](9-), with a lone-pair-containing As-III heteroatom, together with two extra tungsten centres and two yttrium cations at the sandwich position, where CH3COO- and Na+ ions act as linkers between the two polyanion units. In addition, we have also synthesized two carbonate-encapsulated germanotungstates(IV), without lone-pair-containing heteroatoms, with the formula [Ln(3)(A-beta-GeW9O34)(2)(CO3)(H2O)(3)](13-) [Ln = Y-III (2) and Yb-III (3)], i.e. Y2K3Na4[Y-3(A-beta-GeW9O34)(2)(CO3)(H2O)(3)]center dot-19H(2)O (2a) and YbK8Na2[Yb(A-beta-GeW9O34)(2)(CO3)(H2O)(3)]center dot 16H(2)O (3a), and characterized them by FT-IR, SC-XRD, TGA and ESI-MS. Here, the lanthanide ions act as linkers, extending the structures into higher dimensions. Sodium and potassium ions also play a key role as linkers, further extending the structure. The packing shows the presence of certain hydrophilic pores within the structure.