| Popis: |
Hydrothermal reactions between incomplete cuboidal cluster aqua complexes [M 3 Q 4 (H 2 O) 9 ] 4 + and M(CO) 6 (M = Mo, W; Q = S, Se) offer easy access to the corresponding cuboidal clusters M 4 Q 4 . The complete series of homometal and mixed Mo/W clusters [Mo x W 4 - x Q 4 (H 2 O) 1 2 ] n + (x = 0-4, n = 4-6) has been prepared. Upon oxidation of the mixed-metal clusters, it is the W atom which is lost, allowing selective preparation of new trinuclear clusters [Mo 2 -WSe 4 (H 2 O) 9 ] 4 + and [MoW 2 Se 4 (H 2 O) 9 ] 4 + . The aqua complexes were converted by ligand exchange reactions into dithiophosphato and thiocyanato complexes, and crystal structures of [W 4 S 4 ((EtO) 2 PS 2 ) 6 ], [MoW 3 S 4 ((EtO) 2 PS 2 ) 6 ], [Mo 4 Se 4 ((EtO) 2 PS 2 ) 6 ], [W 4 Se 4 ((i-PrO) 2 PS 2 ) 6 ], and (NH 4 ) 6 [W 4 Se 4 (NCS) 1 2 ].4H 2 O were determined. Cyclic voltammetry was performed on [Mo x W 4 - x Q 4 (H 2 O) 1 2 ] n + , showing reversible redox waves 6+/5+ and 5+/4+. The lower oxidation states are more difficult to access as the number of W atoms increases. The [Mo 2 WSe 4 (H 2 O) 9 ] 4 + and [MoW 2 Se 4 -(H 2 O) 9 ] 4 + species were derivatized into [Mo2WSe4(acac)3(py)3]+ and [MoW2Se4(acac)3(py)3]+, which were also studied by CV. When appropriate, the products were also characterized by FAB-MS and NMR ( 3 1 P, 1 H) data. |
