钼过氧配合物与HSO_3^-在酸性溶液中的反应动力学和机理  

The Kinetic and Mechanistic Studies of Reduction Reaction of the Peroxo Complex of Molybdenum with HSO_3^- in Acidic Solution

作　　者：蒋安仁[1] 徐天舒[1] 王志宏[1] 许新华[1] 邓景发[1] 

机构地区：[1]复旦大学化学系,上海200433

出　　处：《化学学报》1993年第6期556-563,共8页Acta Chimica Sinica

摘　　要：用截流法研究了Mm_4O_(12)(O_2)_2^(4-)[简作Mo_4(O_2)_2]与HSO_3^-在酸性条件(4×10^(-3)～0.5mol·dm^(-3))下的反应动力学,并提出了反应机理. 反应经历下列历程: Mo_4(O_2)_2+H_2O(?)Mo_4(O_2)(OOH)(k_1,k_(-1)) Mo_4(O_2)(OOH)+HSO_3^-(?)Mo_4(O_2)OOSO_2+H_2O(k_2,k_(-2)) Mo_4(O_2)OOSO_2+H^++H_2O→Mo_4(O_2)+H_2SO_4(k_3)中间产物Mo_4(O_2)再以相同机理继续与HSO_3^-反应.由机理,得到了[S(IV)]/k_(观察)与[H^+],[S(IV)]之间的线性关系式以及20℃时的动力学参数:k_1=7.4±0.3dm^3·mol^(-1)·s^(-1),k_(-1)/k_2=(5.8±0.5)×10^(-2)和k_(-2)/k_3=(1.4±0.8)×10^(-4).配合物Mo_4(O_2)_2中(O_2)基质子化是决定反应速度的关键步骤.用此机理讨论了Thompson研究的MoO(O_2)_2与HSO_3^-的反应结果.A stopped-flow kinetic Studies of the reduction of peroxomolybdnum (Ⅵ) Mo_4O_(12)(O_2)_2^(4-) with HSO_3^-in aqueous solutions containing 4×10^(-3)～0.50mol·dm^(-3) HClO_4 was performed. A reaction scheme in accord with the experimental results was proposed to be: The steady-state approximation was applied to the postulated intermediates and the rate expression was proposed to be: The following kinetic parameters were determined at 20℃ and I=0.5mol/dm^3: In above mechamism the protonation step of the (O_2^(2-)) ligand in the peroxo complex has a rate slower than the nucleophilic displacement step. The previous result of Thompson's studies on the reactions MoO(O_2)_2 and HSO_3^-was also discussed and compared with our results.

关 键 词：钼过氧配合物 反应动力学 反应机理 

分 类 号：O614.612[理学—无机化学]