Closing the Loop on Transition-Metal-Mediated Nitrogen Fixation: Chemoselective Production of HN(SiMe 3 ) 2 from N 2 , Me 3 SiCl, and X—OH (X = R, R 3 Si, or Silica Gel)
Closing the Loop on Transition-Metal-Mediated Nitrogen Fixation: Chemoselective Production of HN(SiMe 3 ) 2 from N 2 , Me 3 SiCl, and X—OH (X = R, R 3 Si, or Silica Gel)
复制标题
过渡金属介导的固氮闭环：从 N 2 、Me 3 SiCl 和 X-OH（X = R、R 3 Si 或硅胶）化学选择性生产 HN(SiMe 3 ) 2
DOI：
10.1021/jacs.7b08859
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发表时间：
2017
影响因子：
15
通讯作者：
Sita, Lawrence R.
中科院分区：
文献类型：
--
作者：
Duman, Leila M.;Sita, Lawrence R.
Mo（IV）末端亚胺配合物（η5-C5Me5）[N(Et)C(Ph)N(Et)]Mo(NSiMe3)(3)，以1:2的iPrOH和Me3SiCl混合物处理，导致Mo（IV）二氯化物（η5-C5Me5）[N(Et)C(Ph)N(Et)]MoCl2(1)的快速生成，HN(SiMe3)2和iPrOSiMe3各生成1个等量。同样，以1:2的Me3SiOH和Me3SiCl混合物提供1，HN(SiMe3)2和O(SiMe3)2。最后，当硅胶与多余的Me3SiCl当量偶联时，也有效地用作XOH试剂，生成1和HN(SiMe3)2。提出的3→1转变机制包括：通过XOH和3的N原子之间的初始氢键，HCl在MoN亚胺键上正式加成，形成内合物tiiib，然后氯离子通过六元过渡态（IV）从Me3SiCl传递到金属中心，产生中间体（η5-C5Me5）[N(Et)C(Ph)N(Et)]Mo(Cl)(NHSiMe3) (V)和xosime3作为副产物。v的新Mo-N氨基键与Me3SiCl的第二等价物进行meta交换，然后生成1和HN（SiMe3）。这些结果有助于完成一个高效的化学循环固氮是由一组良好表征过渡金属配合物介导。
Treatment of the Mo(IV) terminal imido complex, (η5-C5Me5)[N(Et)C(Ph)N(Et)]Mo(NSiMe3) (3), with a 1:2 mixture of iPrOH and Me3SiCl resulted in the rapid formation of the Mo(IV) dichloride, (η5-C5Me5)[N(Et)C(Ph)N(Et)]MoCl2(1), and the generation of 1 equiv each of HN(SiMe3)2and iPrOSiMe3. Similarly, a 1:2 mixture of Me3SiOH and Me3SiCl provided1, HN(SiMe3)2, and O(SiMe3)2. Finally, silica gel, when coupled with excess equivalents of Me3SiCl, was also effectively used as the XOH reagent for the generation of1and HN(SiMe3)2. A proposed mechanism for the3→1transformation involves formal addition of HCl across the MoN imido bond through initial hydrogen-bonding between XOH and the N-atom of3to form the adductIIIb, followed by chloride delivery from Me3SiCl to the metal center via a six-membered transition state (IV) that leads to the intermediate, (η5-C5Me5)[N(Et)C(Ph)N(Et)]Mo(Cl)(NHSiMe3) (V), and XOSiMe3as a co-product. Metathetical exchange of the new Mo–N amido bond ofVby a second equivalent of Me3SiCl then generates1and HN(SiMe3). These results serve to complete a highly efficient chemical cycle for nitrogen fixation that is mediated by a set of well-characterized transition-metal complexes.