Studies relevant to catalytic reduction of dinitrogen to ammonia by molybdenum triamidoamine complexes.
Studies relevant to catalytic reduction of dinitrogen to ammonia by molybdenum triamidoamine complexes.
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DOI：
10.1021/ic040095w
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发表时间：
2005-01
影响因子：
4.6
通讯作者：
D. Yandulov;R. Schrock
中科院分区：
文献类型：
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作者：
D. Yandulov;R. Schrock
本文探讨了含[(HIPTNCH2CH2)3N]3-配体(HIPT=3，5-(2，4，6-i-Pr3C6H2)2C6H3)的钼化合物催化还原氮的几个问题。另外四个在催化氮氮还原反应中可能的中间体现在已经被晶体结构表征：它们是：MON=NH(Mo=[(HIPTNCH2CH2)3N]Mo)，[Mo=NNH2][bar‘4](Ar’=3，5-(CF3)2C6H3)，[Mo=NH][bar‘4]和Mo(NH3)。我们还研究了用[2，6-Luth][B(C6F5)4]与MoH反应生成的2，6-Lutidine络合物Mo(2，6-Lut)+。我们着重于尚未分离的化合物的合成，包括Mo=NNH_2，Mo=NH和Mo(NH_2)。未观察到[Mo=NNH2]+还原生成的Mo=NNH2。它分解得到含有以下两种或两种以上化合物的混合物：MON=NH、Mo三键N、Mo(NH3)+、Mo(NH3)和氨。Mo=NH可通过[Mo=NH]+还原而成，在少量CrCp*2存在下长期稳定，但在没有CrCp*2的情况下，在Mo=NH+催化剂存在下，Mo=NH缓慢转化为Mo三键N和Mo(NH2)的混合物。在四氢呋喃中，Mo(NH_3)~+与Li(SiMe_3)_2去质子化可独立生成Mo(NH_2)，但经分离后可分解为Mo三键N。尽管氮素的催化还原可能涉及多达14个“线性”中间体，包括“外部”质子和/或电子的添加，但现在看来，其中几个中间体，连同氨和/或氢气，可以在中间体之间的几个反应中产生，这些中间体本身就是质子和/或电子源。
In this paper we explore several issues surrounding the catalytic reduction of dinitrogen by molybdenum compounds that contain the [(HIPTNCH2CH2)3N]3- ligand (where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3). Four additional plausible intermediates in the catalytic dinitrogen reduction have now been crystallographically characterized; they are MoN= NH (Mo = [(HIPTNCH2CH2)3N]Mo), [Mo=NNH2][BAr'4] (Ar' = 3,5-(CF3)2C6H3), [Mo=NH][BAr'4], and Mo(NH3). We also have crystallographically characterized a 2,6-lutidine complex, Mo(2,6-Lut)+, which is formed upon treatment of MoH with [2,6-LutH][B(C6F5)4]. We focus on the synthesis of compounds that have not yet been isolated, which include Mo=NNH2, Mo=NH, and Mo(NH2). Mo=NNH2, formed by reduction of [Mo=NNH2]+, has not been observed. It decomposes to give mixtures that contain two or more of the following: MoN=NH, Mo triple bond N, Mo(NH3)+, Mo(NH3), and ammonia. Mo=NH, which can be prepared by reduction of [Mo=NH]+, is stable for long periods in the presence of a small amount of CrCp*2, but in the absence of CrCp*2, and in the presence of Mo=NH+ as a catalyst, Mo=NH is slowly converted into a mixture of Mo triple bond N and Mo(NH2). Mo(NH2) can be produced independently by deprotonation of Mo(NH3)+ with LiN(SiMe3)2 in THF, but it decomposes to Mo triple bond N upon attempted isolation. Although catalytic reduction of dinitrogen could involve up to 14 intermediates in a "linear" sequence that involves addition of "external" protons and/or electrons, it seems likely now that several of these intermediates, along with ammonia and/or dihydrogen, can be produced in several reactions between intermediates that themselves behave as proton and/or electron sources.