Synthesis and Molecular Design of Novel Modified-Heteropolyanions Containing Multicenter Active Sites

1.合成了1，4，9-三钒(V)取代的Keggin多氧钨酸盐[1，4，9-PW_9V_3O_(1，4，9-PW_9V_3O_(？)产物中还含有[Cp^*Rh(DMSO)_3]和[Cp^*Rh(DMSO)_3]；在水溶液中还进行了超速离心法测定分子量(MW)。两个固相钛酸根取代化合物分别是两个α-Keggin[1，2，3-PW_9Ti_3O_&lt；40&gt；]^&lt；9-&gt；和两个新的α-Keggin[1，2-Pw_2O_&lt；10&gt；Ti_2O_&lt；40&gt；]^&lt；7-gt；单元的二聚钛-氧-钛酸酐。溶液相对分子质量测量表明，前者在pH 7.0水溶液中为二聚体，而后者在pH 7.8水溶液中为单体。合成了三金属取代的Dawson多氧钨酸盐[P_2W_&lt；15&gt；M_3O_&lt；62&gt；]^&lt；9-&gt；(M=Nb^V，V^V)与有机金属基团(Cod)Pt^&lt；2+&gt；和Cp^*Rh^&lt；2+&gt；形成的负载型多氧钨酸盐，阐明了多氧阴离子载体(Nb vs.V)与有机金属物种(Cod)(Cp^Rh^&lt；2+&gt；)之间的相互作用。用GC/MS分析了几种钒(V)取代的Keggin和Dawson多金属氧酸盐催化30%H_2O_2氧化甲苯和硝基苯的产物。对通过离子机制和自由基机制促进反应的多金属氧酸盐进行了分类。

Several novel results in this research were obtained :1. The Cp^*Rh^<2+> complex (Cp^* = C_5Me_5) supported on the V_3 surface (B-site) of 1, 4, 9-tri-vanadium(V)-substituted Keggin polyoxotungstate [1, 4, 9-PW_9V_3O_<40>]^<6-> was synthesized. The product also contained [Cp^*Rh(DMSO)_3]^<2+> as counterion.2.Tri-Ti^<IV>-and di-Ti^<IV>-substituted Keggin polyoxotungstate were isolated as potassium salts and their X-ray crystal structures determined. Ultracentrifugation molecular weight (MW) measurements were also performed in aqueous solution. The two Ti^<IV>-substituted compounds in the solid state were dimeric, Ti-O-Ti anhydride forms of two α-Keggin [1, 2, 3-PW_9Ti_3O_<40>]^<9-> units and of two novel α-Keggin [1, 2-PW_<10>Ti_2O_<40>]^<7-> units, respectively. Solution MW measurements showed that the former was a dimer in pH7.0 aqueous solution, whereas the latter was a monomer in pH 7.8 aqueous solution.3. The supported-polyoxotungstates formed between tri-metal-substituted Dawson polyoxotungstate [P_2W_<15>M_3O_<62>]^<9-> (M = Nb^V, V^V) and organometallic groups ((cod)Pt^<2+> and Cp^*Rh^<2+>) were synthesized, and the effects polyoxoanion-support (Nb vs. V) and organometallic species ((cod)Pt^<2+> vs. Cp^*Rh^<2+>) were elucidated.4. Oxidation products of toluene and nitrobenzene with 30% aqueous H_2O_2 catalyzed by several vanadium(V)-substituted Keggin and Dawson polyoxometalates were carefully analyzed by GC/MS measurements. Polyoxometalates which promote the reaction via an ionic mechanism and via a radical mechanism were classified.