Os_(3)(CO)_(12)及其膦取代衍生物氧原子转移反应动力学与机理研究

Kinetics and Mechanism of Oxygen Atom Transfer Reactions to Os_(3)(CO)_(12) and Its Phosphine Substituted Derivatives

报道了(CH_(3))_(3)NO存在条件下Os_(3)(CO)_(12)和Os_(3)(CO)11L(L=PPh_(3),P(n-Bu)_(3),AsPh_(3))分别在CH_(2)Cl_(2)-C_(2)H_(5)OH和CH_(2)Cl_(2)溶剂中职代羰基反应的动力学数据。结果表明,反应遵循单项缔合速度定律,与外来配体L的浓度无关。定量地研究了溶剂中乙醇的浓度对反应速度的影响,并讨论了反应机理、过渡态和中间体可能的结构及取代配体的影响。

Detailed kinetic data are reported for the reactions of CO substitution of Os_(3)(CO)12 and Os_(3)(CO)11L (where L = PPh_(3), AsPh_(3), P(n-Bu)_(3)) in CH_(2)Cl_(2)-C_(2)H_(5)OH and CH_(2)Cl_(2) respectively in the presence of Me_(3)NO. The results indicate that the reactions follow associative rate law, that is, r = k2[complex][Me_(3)NO], and are independent of entering ligand concentration. The effect of C_(2)H_(5)OH as solvent on the reactions has been investigated quantitatively. Reaction mechanism, structures of transition states and intermediates have been proposed. The ligand effects on the reactions have been discussed as well.