Amide versus amine ligand paradigm in the direct amination of alcohols with Ru-PNP complexesElectronic supplementary information (ESI) available. See DOI: 10.1039/c8cy00869h

• Main Authors: Pingen, Dennis, Choi, Jong-Hoo, Allen, Henry, Murray, George, Ganji, Prasad, van Leeuwen, Piet W. N. M, Prechtl, Martin H. G, Vogt, Dieter
• Format: Article
• Language: English
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/c8cy00869h

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. Ruthenium complexes of PNP-ligands bearing secondary amines were found to be inactive in the alcohol amination with NH 3 , while all complexes of homologous ligands bearing tertiary amines gave active catalysts!