Polyoxovanadates:  High-Nuclearity Spin Clusters with Interesting Host−Guest Systems and Different Electron Populations. Synthesis, Spin Organization, Magnetochemistry, and Spectroscopic Studies

The compounds Cs12[VIV18O42(H2O)]·14H2O (1a), K12[VIV18O42(H2O)]·16H2O (1b), Rb12[VIV18O42(H2O)]·19H2O (1c), K9[H3VIV18O42(H2O)]·14H2O·4N2H4 (1d), K11[H2VIV18O42(Cl)]·13H2O·2N2H4 (2a), K9[H4VIV18O42(Br)]·14H2O·4N2H4 (2b), K9[H4VIV18O42(I)]·14H2O·4N2H4 (2c), K10[H3VIV18O42(Br)]·13H2O·0.5N2H4 (2d), K9[H4VIV18O42(NO2)]·14 H2O·4N2H4 (3), Cs11[H2VIV18O42(SH)]·12H2O (4), K10[HVIV16VV2O42(Cl)]·16H2O (5a), Cs9[H2VIV16VV2O42(Br)]·12H2O (5b), K10[HVIV16VV2O42(Br)]·16H2O (5c), Cs9[H2VIV16VV2O42(I)]·12H2O (5d), K10[HVIV16VV2O42(I)]·16H2O (5e), K10[HVIV16VV2O42(HCOO)]·15H2O (6), (NEt4)5[VIV10VV8O42(I)] (7), and Na6[H7VIV16VV2O42(VO4)]·21H2O (8) have been characterized by elemental analyses, redox titrations, IR and EPR spectroscopy, and magnetic susceptibility measurements, as well as by single crystal X-ray structure analyses. The anions containas a common structural featurean approximately spherical {V18O42} shell, which can act as a unique host system for neutral and anionic guests. Remarkably, the electron population of these clusters candepending on the specific reaction conditionsbe varied in a wide range between 10 and 18 3d electrons without changing the overall structure. The related magnetic properties in connection with the phenomenon of electron-dependent spin organization on a spherical cluster shell have been discussed in detail.