Development of Catalytic Reaction Fiekl From Nano-to Subnano-Scale by Utilizing Properties of Large Oxide Cluster

the dinuclear peroxotungstate, k2 [{w (o 2) _ (= o) 2 (2 h o)} _ 2(μ- o)] 2·2 h o (w2),could act as an effective epoxidation catalyst using h_2_2 in water under mild reaction conditions。further,我们联合组织-inorganic hybrid support materials by covalently anchoring dihydroimidazoriumbased ionic liquid fragments onto the sio_2 to heterogenize W2 for the development of recoverableand recyclable epoxidation catalysts.The epoxidation with h_2_2 catalyzed by lacunarysilicodecatungstate ([γ- siw_< 10> o_< 34>(h_2o)_2]^<4->) proceeded with【greater than or equal】99%selectivity to epoxide，【greater than or equal】99% efficiency of h_2_2 utilization，high stereospecificity . a novel s - shaped disilicoeicosatungustate,[(γ- siw _< 10 > o _< 32 >(h 2 o 2)_)_ 2(4μ- o)_ 2]^< ->,已确定的定义定义类型a partially protonated divacant lacunary Keggin-typepolyoxometalate,[γ- siw _ < 10 > o ^ < 34 > (h 2 o) _ 2] ^ < 4 - >,in an anhydrous organic solvent with cf_3 so_3 H. in contrast，the dimerization of ([γ- siw_< 10> o_< 34>(h_2o)_2] <4-> without cf_3 so_3h results in the formation of aclosed-shape cluster,([γ- siw _< 10 > o _< 32 >_ 2(4μ- o)_]^< 8 ->. while([γ- siw _< 10 > o _< 34 >(h 2 o 2]^<)_ 4 -> and([γ- siw _ < 10 > o < 32 >译文:2(μ- o) 4] ^ < 8 - > with the common [siw _ < 10 > o ^ < 32 >] fragment are almost inactive,the S-shaped cluster ([γ- siw_< 10> o_< 34>(h_2o)_2]^<4-> efficiently promotes the h_2_2 -basedbaeer - villiger oxidations of cycloalkanones.On the other hand，a novel titanium-substituted silicotungstate cluster of ([γ- sit_2 w_ <10> o_ <36>(OH)_2}_]^<8-> issynthesized by the introduction of titanium(IV) ions into a divacant lacunary γ-Keggin-typesilicotungstate of ([γ- siw_c <10> o_c <36>] . This titanium-substituted polyoxometalate exhibits adimeric structure The epoxidation with ([γ- siti_2 w_< 10> o_< 36>(oh_2)]^<8-> is stereospecific。

The dinuclear peroxotungstate, K2[{W(=O)(O_2)_2(H_2O)}_2(μ-O)]・2H_2O (W2), could act as an effective epoxidation catalyst using H_2O_2 in water under mild reaction conditions. Further, we synthesized organic-inorganic hybrid support materials by covalently anchoring dihydroimidazorium based ionic liquid fragments onto the SiO_2 to heterogenize W2 for the development of recoverable and recyclable epoxidation catalysts.The epoxidation with H_2O_2 catalyzed by lacunary silicodecatungstate ([γ-SiW_<10>O_<34>(H_2O)_2]^<4->) proceeded with 【greater than or equal】99% selectivity to epoxide, 【greater than or equal】99% efficiency of H_2O_2 utilization, high stereospecificity.A novel S-shaped disilicoeicosatungustate, [(γ-SiW_<10>O_<32>(H_2O)_2)_2(μ-O)_2]^<4->, is obtained by dehydrative condensation of a partially protonated divacant lacunary Keggin-type polyoxometalate, [γ-SiW_<10>O^<34>(H_2O)_2]^<4->, in an anhydrous organic solvent with CF_3SO_3H. In contrast, the dimerization of ([γ-SiW_<10>O_<34>(H_2O)_2]^<4-> without CF_3SO_3H results in the formation of a closed-shape cluster, ([γ-SiW_<10>O_<32>_2(μ-O)_4]^<8->. While ([γ-SiW_<10>O_<34>(H_2O)_2]^<4-> and ([γ-SiW_<10>O_<32>_2(μ-O)_4]^<8-> with the common [SiW_<10>O^<32>] fragment are almost inactive, the S-shaped cluster ([γ-SiW_<10>O_<34>(H_2O)_2]^<4-> efficiently promotes the H_2O_2-based Baeyer-Villiger oxidations of cycloalkanones.On the other hand, a novel titanium-substituted silicotungstate cluster of ([γ-SiTi_2W_<10>O_<36>(OH)_2}_]^<8-> is synthesized by the introduction of titanium(IV) ions into a divacant lacunary γ-Keggin-type silicotungstate of ([γ-SiW_<10>O_<36>]^<8->. This titanium-substituted polyoxometalate exhibits a dimeric structure The epoxidation with ([γ-SiTi_2W_<10>O_<36>(OH)_2]^<8-> is stereospecific.