Résumé
The intrinsic reactivity of the organoruthenium-grafted tungstophosphates [a-PW11O39{Ru(h6-arene)(H2O)}]5- and [a-PW11O39{Ru(DMSO)3(H2O)}]5- has been studied as a prerequisite for later catalytic studies. Upon reflux in aqueous solution, they partially transform into [{PW11O39Ru(h6-arene)}2{WO2}]8- (when arene = benzene, toluene. . .) and [a-PW11O39{Ru(DMSO)}]5-, respectively. In the former case, the conversion is markedly increased by deliberate addition of tungstate: through a solution NMR study, we show that [{PW11O39Ru(h6-p-cymene)}2{WO2}]8- is quantitatively obtained by refluxing a 2:1:2 mixture of [a-PW11O39]7-, [Ru(h6-p-cymene)Cl2]2 and [WO4]2- at pH 3. In contrast, a different type of complex, [{PW11O39Ru(DMSO)3}2{(WO2(H2O))2O}]8-, is formed by reaction of [a-PW11O39{Ru(DMSO)3(H2O)}]5- with tungstate; it has been characterized by single crystal X-ray diffraction analysis of an acidic potassium salt, and by 183W solution NMR. The more sterically demanding {Ru(DMSO)3}2+ fragment probably does not allow the formation of {PW11O39Ru(DMSO)3}2{WO2}]8-, while connection of {PW11O39Ru(DMSO) }5- subunits is possible through the larger {(WO2(H O))2O}2+ bridge.