Synthesis and characterization of carbonate‐encapsulated ytterbium‐ and yttrium‐containing polyoxotungstates

A sandwiched‐type carbonate‐encapsulated yttrium‐containing arsenotungstate(III) has been synthesized under mild reaction conditions. The polyanion [NaCH 3 COO{Y 2 (H 2 O) 3 (B‐α‐AsW 9 O 33 ) 2 (W 2 O 5 )(CO 3 )}] 12− ( 1 ) was isolated as a solid crystalline material by the reaction of a Y III salt with the sodium salt of trilacunary [AsW 9 O 33 ] 9− in sodium acetate solution. The sodium salt of the polyanion, i.e. Na 12 [Na(CH 3 COO){Y 2 (AsW 9 O 33 ) 2 (W 2 O 5 )(CO 3 )(H 3 O) 3 }]·22H 2 O ( 1a ), was characterized by various analytical techniques, such as FT–IR, single‐crystal X‐ray diffraction (SC–XRD), TGA (thermogravimetric analysis), 13 C NMR and ESI–MS (electrospray ionization mass spectrometry). SC–XRD studies revealed that the polyanion crystallizes in the triclinic space group P . The structure showed that the polyanion is a carbonate‐encapsulated sandwich‐type species, consisting of two trilacunary B‐α‐[AsW 9 O 33 ] 9− , with a lone‐pair‐containing As III heteroatom, together with two extra tungsten centres and two yttrium cations at the sandwich position, where CH 3 COO − 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‐β‐GeW 9 O 34 ) 2 (CO 3 )(H 2 O) 3 ] 13− [Ln = Y III ( 2 ) and Yb III ( 3 )], i.e. Y 2 K 3 Na 4 [Y 3 (A‐β‐GeW 9 O 34 ) 2 (CO 3 )(H 2 O) 3 ]·19H 2 O ( 2a ) and YbK 8 Na 2 [Yb(A‐β‐GeW 9 O 34 ) 2 (CO 3 )(H 2 O) 3 ]·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.