Application of Ni(II) complexes of air stable Schiff base functionalized N-heterocyclic carbene ligands as catalysts for the transfer hydrogenation of aliphatic ketones
New air stable N-heterocyclic carbene functionalized Schiff base ligands (L) of the type 2-[-2-[3-(R)imidazol-1-yl]ethyliminomethyl]phenol [R = methyl (2), 2-pyridylmethyl (3)] were synthesized and characterized by NMR, IR, MS, and CHN analysis. Single
crystal X-ray structural analysis of their Ni(II) complexes revealed square planar arrangement of the chelating ligands coordinated in tridentate (2, C^N^O) and tetradentate (3, N^C^N^O) modes around the metal. The three new isolated and fully characterized complexes were utilized
as catalysts for the catalytic transfer hydrogenation of aliphatic ketones in 2-propanol as solvent and source of hydrogen. Based on 0.2 mol% catalyst concentration, the complexes showed activity for aliphatic ketones and 100% conversion (turnover number of 500) for cyclohexanone and
all the aromatic ketones tested.
Keywords: Catalytic transfer hydrogenation; N-heterocyclic carbene; Schiff base; aliphatic ketones; nickel complexes; solvent-free
Document Type: Research Article
Affiliations: School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa
Publication date: 17 September 2018
- Access Key
- Free content
- Partial Free content
- New content
- Open access content
- Partial Open access content
- Subscribed content
- Partial Subscribed content
- Free trial content