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 containas a common structural featurean
approximately spherical {V18O42} shell,
which can act
as a unique host system for neutral and anionic guests.
Remarkably, the electron population of these clusters
candepending on the specific reaction conditionsbe 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.