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Graphical abstract Highlights • New multidentate Schiff base-NHC ligand was synthesised. • Synthetic route to a new multinuclear Ni complex was developed. • High activity for catalytic transfer hydrogenation achieved with TOF up to 2000 h−1. • Full characterisation of both ligand and complex achieved. Abstract A new Schiff base-functionalized N -heterocyclic carbene ligand precursor 3-benzyl-1-[2-((2-hydroxy-benzylidene)-amino]-ethyl-3 H -imidazol-1-ium bromide (3), and its trinuclear Ni(II) complex [LNiL-Ni-LNiL].2Br (4) where L = 2-[2-(3-benzylimidazol-1-yl) ethyliminomethyl]phenol, were synthesized via the solventless and free carbene routes respectively. Both compounds were characterized by spectroscopic and X-ray diffraction techniques. Single crystal XRD analysis of 4 showed that it is composed of a central square planar Ni(II) ion symmetrically linked to two distorted square planar Ni(II) ions via two bridging ligands. The central Ni(II) ion is only bound to the Schiff base moieties of the bridging ligands via the phenolate oxygen donor (O1) and imine nitrogen donor (N1) atoms in a trans [N^O^(Ni2+)^N^O] mode, whilst the carbene moieties of each bridging ligand and a tridentate L are coordinated in a distorted square planar C NHC -(Ni2+)^N^O^C NHC mode to stabilise each of the terminal Ni(II) ions. Complex 4 showed significant activity as a catalyst in the transfer hydrogenation of a range of aliphatic and aromatic ketones, at a catalyst concentration of 0.1 mol%. An excellent conversion up to 100% was achieved for aromatic ketones after 4 h. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]