State Key Laboratory of Chemical Resource Engineering, Institute of Materia Medica, College of Science, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
Phys Chem Chem Phys. 2013 Jan 21;15(3):901-10. doi: 10.1039/c2cp43401f.
In this paper, the reaction mechanisms of CO assisted N(2) cleavage and functionalization activated by a dinuclear hafnium complex are studied using a density function theory (DFT) method. Several key intermediates (Ia, Ib, Ic and Id) with axial/equatorial N=C=O coordination structures are found to be of importance along reaction pathways of CO assisted N(2) functionalization, which could provide a profound theoretical insight into the C-N bond formation and N-N bond cleavage. There are two different attack directions to insert the first CO molecule into the Hf-N bonds of the dinuclear hafnium complex, which lead to C-N bond formation. The calculated results imply that CO insertion into the Hf(1)-N(3) bond (Path A1) reacts more easily than that into the Hf(2)-N(3) bond (Path A3). But for the insertion of the second CO insertion to give 2A, there are two possibilities (Path A1 and Path A2) according to this insertion being after/before N-N bond cleavage. Two pathways (Path A1 and Path A2) are proved to be possible to form final dinitrogen functionalized products (oxamidide 2A, 2B and 2C) in this study, which explain the formation of different oxamidide isomers in CO assisted N(2) functionalization activated by a dinuclear hafnium complex.
本文使用密度泛函理论（DFT）方法研究了双核铪配合物促进的 CO 协助的 N(2)裂解和功能化的反应机理。在 CO 协助的 N(2)功能化反应途径中，发现具有轴向/赤道 N=C=O 配位结构的几个关键中间体（Ia、Ib、Ic 和 Id）非常重要，这为 C-N 键形成和 N-N 键断裂提供了深刻的理论见解。第一个 CO 分子有两种不同的进攻方向插入双核铪配合物的 Hf-N 键，导致 C-N 键形成。计算结果表明，CO 插入 Hf(1)-N(3)键（Path A1）比插入 Hf(2)-N(3)键（Path A3）更容易反应。但对于第二个 CO 的插入以给出 2A，根据此插入是在 N-N 键断裂之前/之后，有两种可能性（Path A1 和 Path A2）。本研究证明了两条途径（Path A1 和 Path A2）有可能形成最终的二氮功能化产物（亚氨基二酰胺 2A、2B 和 2C），这解释了在双核铪配合物促进的 CO 协助的 N(2)功能化中不同亚氨基二酰胺异构体的形成。
