The catalytic activity of a series of Ru-PNP pincer ligand complexes was studied in the direct amination of alcohols with ammonia. It turned out that all complexes of PNP ligands bearing a secondary amine showed no activity in this hydrogen-shuttling reaction sequence, while all complexes of homologous ligands bearing a tertiary amine gave active catalysts. Further comparative studies on catalysts bearing an acridine-based PNP pincer ligand and a PNP ligand of the Xantphos family provided valuable mechanistic insight that led to the design of a highly active catalyst. It appears that in the group of ligands studied here only ligands that do not form stable Ru-amido complexes are active alcohol amination catalysts.

中文翻译：

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用Ru-PNP配合物直接胺化醇时的 酰胺对胺配体范式†

研究了一系列Ru-PNP钳形配体配合物在醇与氨的直接胺化反应中的催化活性。结果表明，带有仲胺的PNP配体的所有配合物在该氢穿梭反应序列中均没有活性，而带有叔胺的同源配体的所有配合物均具有活性催化剂。对带有bearing啶基PNP钳形配体和Xantphos家族的PNP配体的催化剂的进一步比较研究提供了有价值的机理见解，从而导致了高活性催化剂的设计。似乎在这里研究的配体组中，仅不形成稳定的Ru-酰胺基络合物的配体是活性醇胺化催化剂。