Synthesis, structures and catalytic activity of 1,3-bis(aryl)triazenide(p-cymene)ruthenium(II) complexes

• Ruthenium triazenide complexes as selective catalysts for hydrogenation of alkenones.
• Intramolecular hydrogen bonding in triazenes and ruthenium triazenide complexes.
• Base free transfer hydrogenation by ruthenium triazenide complexes.

The synthesis, characterization, crystal structures and catalytic activity of four new 1,3-bis(aryl)triazenide(p-cymene)ruthenium(II) complexes bearing methoxycarbonyl (5), hydroxymethyl (6), acetylphenyl (7) in the ortho position, and methyl in the para position (8) of the bis(aryl)triazenide ligand are reported. These complexes were used as catalysts in the transfer hydrogenation reactions of ketones and alkenone with good to excellent yields of the corresponding alcohol. Remarkable differences in yields were obtained with those complexes with ortho substituents on the aryl group of the triazenide ligand (5–7) compared to that without ortho substituent (8). Good selectivity was also observed in the reduction of the alkenone towards the carbonyl group.

Ortho substituents on the aryl group of the triazenide ligand in ruthenium complexes, enhance their activity as catalysts in the transfer hydrogenation of acetophenone.Figure optionsDownload as PowerPoint slide