NEW PERSPECTIVES IN POLYOXOMETALATE CHEMISTRY BY ISOLATION OF COMPOUNDS CONTAINING VERY LARGE MOIETIES AS TRANSFERABLE BUILDING-BLOCKS - (NME4)5[AS2MO8V4ASO40]CENTER-DOT-3H2O, (NH4)21[H3MO57V6(NO)6O183(H2O)18]CENTER-DOT-65H2O, (NH2ME2)18(NH4)6[MO57V6(NO)6O183(H2O)18]CENTER-DOT-14H2O, AND (NH4)12[MO36(NO)4O108(H2O)16]CENTER-DOT-33H2O

The compounds (NMe4)5[As2Mo8V4AsO40] . 3 H2O 2a, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] . 65 H2O 3a, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] . 14 H2O 3b and (NH4)12[Mo36(NO)4O108(H2O)16] . 33 H2O 4a (3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3 a, 3 b, and 4 a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of ''extremely'' large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo17} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na3(NH4)12[H15Mo57Fe6(NO)6O183(H2O)18] . 76H2O 7a.