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

The compounds Cs 12 [V IV 18 O 42 (H 2 O)]·14H 2 O ( 1a ), K 12 [V IV 18 O 42 (H 2 O)]·16H 2 O ( 1b ), Rb 12 [V IV 18 O 42 (H 2 O)]·19H 2 O ( 1c ), K 9 [H 3 V IV 18 O 42 (H 2 O)]·14H 2 O·4N 2 H 4 ( 1d ), K 11 [H 2 V IV 18 O 42 (Cl)]·13H 2 O·2N 2 H 4 ( 2a ), K 9 [H 4 V IV 18 O 42 (Br)]·14H 2 O·4N 2 H 4 ( 2b ), K 9 [H 4 V IV 18 O 42 (I)]·14H 2 O·4N 2 H 4 ( 2c ), K 10 [H 3 V IV 18 O 42 (Br)]·13H 2 O·0.5N 2 H 4 ( 2d ), K 9 [H 4 V IV 18 O 42 (NO 2 )]·14 H 2 O·4N 2 H 4 ( 3 ), Cs 11 [H 2 V IV 18 O 42 (SH)]·12H 2 O ( 4 ), K 10 [HV IV 16 V V 2 O 42 (Cl)]·16H 2 O ( 5a ), Cs 9 [H 2 V IV 16 V V 2 O 42 (Br)]·12H 2 O ( 5b ), K 10 [HV IV 16 V V 2 O 42 (Br)]·16H 2 O ( 5c ), Cs 9 [H 2 V IV 16 V V 2 O 42 (I)]·12H 2 O ( 5d ), K 10 [HV IV 16 V V 2 O 42 (I)]·16H 2 O ( 5e ), K 10 [HV IV 16 V V 2 O 42 (HCOO)]·15H 2 O ( 6 ), (NEt 4 ) 5 [V IV 10 V V 8 O 42 (I)] ( 7 ), and Na 6 [H 7 V IV 16 V V 2 O 42 (VO 4 )]·21H 2 O ( 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 {V 18 O 42 } 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.