Catalytic reduction of dinitrogen to ammonia at a single molybdenum center
Catalytic reduction of dinitrogen to ammonia at a single molybdenum center
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DOI：
10.1073/pnas.0602778103
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发表时间：
2005-12
期刊：
影响因子：
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通讯作者：
Walter W. Weare;X. Dai;M. J. Byrnes;J. Chin;R. Schrock;P. Müller
中科院分区：
文献类型：
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作者：
Walter W. Weare;X. Dai;M. J. Byrnes;J. Chin;R. Schrock;P. Müller
自从我们发现在单一钼中心将二氮催化还原为氨以来，我们已经开始了各种旨在进一步了解这一复杂反应循环的研究。这些研究包括单个反应步骤和配体变化的研究。反应顺序中的一个重要步骤是中性钼（III）化合物中氨与二氮的交换。我们已经发现，这种交换反应在二氮中是一级的，并且在1个大气压的二氮下相对较快（在<1小时内完成）。在三酰氨基胺配体中的三联苯取代基的变化表明，原始配体在其产生成功的催化剂的能力方面不是唯一的。然而，含有空间要求较低的配体的络合物不能催化从二氮形成氨;它被提议作为二氮烯基（MoNNH）中间体的碱催化分解的结果。
Since our discovery of the catalytic reduction of dinitrogen to ammonia at a single molybdenum center, we have embarked on a variety of studies designed to further understand this complex reaction cycle. These include studies of both individual reaction steps and of ligand variations. An important step in the reaction sequence is exchange of ammonia for dinitrogen in neutral molybdenum(III) compounds. We have found that this exchange reaction is first order in dinitrogen and relatively fast (complete in <1 h) at 1 atm of dinitrogen. Variations of the terphenyl substituents in the triamidoamine ligand demonstrate that the original ligand is not unique in its ability to yield successful catalysts. However, complexes that contain sterically less demanding ligands fail to catalyze formation of ammonia from dinitrogen; it is proposed as a consequence of a base-catalyzed decomposition of a diazenido (MoNNH) intermediate.