Electron-Rich Mo -Polyoxomolybdates Resembling the Paratungstic Archetype.

The first polyoxometalates (POMs) composed of Mo , Mo , discrete d -Mo and Mo , [Mo Mo Mo O (μ -OH)(μ -OH)py ] (1), was prepared from the solvothermal partial oxidation of [Mo O (O CCH ) (H O) ]ZnCl in a mixture of pyridine and water. The Mo =O adduct-free unit [H Mo O py ] presents the 11e-reduced Mo derivative of the paratungtic archetype. The use of methanol, ethanol, n-propyl alcohol and triglycol instead of water produced the isostructural [Mo Mo Mo O (μ -OH)(μ -OR)py ](R=CH , 2; C H , 3; C H , 4; C H OH, 5), providing the first examples of Mo -POMs containing bridging alkoxyl groups. The addition of [Cr Mo O ] led to the substitution of {Mo =O} with {Cr -py} in the allomer [Mo Mo Mo Cr O (μ-OH) py ] (6). Using a mixture of Mo and MoW precursors afforded W -incorporated allomer [Mo Mo Mo W O (μ-OH) py ] (7). The complete substitution of Mo with W by using a mixture of the Mo W, MoW and W precursors produced the diamagnetic [Mo Mo W O (μ -OH)py ] (syn-8) resulting from the anti→syn conversion between the top and bottom M triads concomitant with Mo -Mo bonding. Both anti-1-7 and syn-8 have been characterized by X-ray single crystal structural analyses. The spin distribution and magnetic interactions have been investigated by temperature-dependent magnetic susceptibility and DFT theoretical calculations. Heterogeneous hydrogen transfer catalysis has been examined by the Lewis catalysis field (LCF) theory.