Synthesis and characterization of oxorhenium(v) diamido pyridine complexes that catalyze oxygen atom transfer reactions.
Synthesis and characterization of oxorhenium(v) diamido pyridine complexes that catalyze oxygen atom transfer reactions.
复制标题
催化氧原子转移反应的氧铼(v)二酰氨基吡啶配合物的合成和表征。
作者：
Cassandra P. Lilly;P. Boyle;Elon A. Ison
详细合成了配合物 1-4，Re(O)(X)(DAP) (X = Me, 1; Cl, 2; I, 3; OTf (triflate), 4)，其中包含二氨基吡啶 (DAP) 辅助配体 (2,6-双((异三叉氨基)甲基)吡啶)，并显示其是 PyO 到 PPh(3) 氧原子转移 (OAT) 反应的有效催化剂。催化活性如下：4≈3 > 2 > 1。观察到的电子趋势与催化循环期间所提出的 Re(VII) 二氧中间体 Re(O)(2)(X)(DAP) 的周转限制还原一致。配合物 1-3 的催化活性与之前发表的 Re(O)(X)(DAAm) 型二酰氨基胺 (DAAm) 氧铼配合物（X = Me, 5; Cl, 6; I, 7 和 DAAm = N,N-双（2-芳基氨基乙基）甲胺）进行了比较，后者在催化反应过程中表现出水解降解。与 5-7 相比，复合物 1-3 显示出更高的周转频率。这种更高的催化活性归因于更刚性的 DAP 配体主链，这使得复合物更不易分解。然而，由于观察到Re(O)(3)((MesNCH(2))(MesNCH)NC(5)H(3)) 8 的DAP配体的一个臂被氧化，因此对该催化系统提出了另一种分解途径。
The detailed syntheses of complexes 1-4, Re(O)(X)(DAP) (X = Me, 1; Cl, 2; I, 3; OTf (triflate), 4) incorporating the diamido pyridine (DAP) ancillary ligand (2,6-bis((mesitylamino)methyl)pyridine) are described and shown to be effective catalysts for oxygen atom transfer (OAT) reactions of PyO to PPh(3). The catalytic activities are as follows: 4≈3 > 2 > 1. The observed electronic trend is consistent with the turnover limiting reduction of the proposed Re(VII) dioxo intermediate, Re(O)(2)(X)(DAP), during the catalytic cycle. The catalytic activity of complexes 1-3 was compared to previously published diamido amine (DAAm) oxorhenium complexes of the type Re(O)(X)(DAAm) (X = Me, 5; Cl, 6; I, 7 and DAAm = N,N-bis(2-arylaminoethyl)methylamine) which exhibit hydrolytic degradation during the catalytic reaction. Complexes 1-3 displayed higher turnover frequencies compared to 5-7. This higher catalytic activity was attributed to the more rigid DAP ligand backbone, which makes the complexes less susceptible to decomposition. However, another decomposition pathway was proposed for this catalytic system due to the observation of Re(O)(3)((MesNCH(2))(MesNCH)NC(5)H(3)) 8 in which one arm of the DAP ligand is oxidized.