New strategies for the generation of large heteropolymetalate clusters: The beta-B-SbW9 fragment as a multifunctional unit

Proceeding from the alpha-B-SbW9O33 fragment 1, various novel large heteropolyanions ([Na2Sb8W36O132(H2O)(4)](12-) (2), [Sb2W22O74(OH)(2)](12-) (3) and [Sb2W20M2O70(H2O)(6)]((14 - 2n)-) (4); Mn+ = Fe3+, Co2+, Mn2+, Ni2+) have been obtained in crystalline form by systematic synthesis, Their unexpected structures have been studied by X-ray diffraction: 2, 3 and 4 contain beta-SbW9 units connected to each other by Sb3+ ions. WO2/WO2OH groups, and WO2/Mn+(H2O)(3) groups, respectively. Structural details and especially the systematic synthesis strategy for the formation of these interesting polytungstates are discussed in order to explain the unusual behaviour of 1 in aqueous solution under different reaction conditions.