Novel ruthenium(II)–N-heterocyclic carbene complexes; synthesis, characterization and catalytic application

• Novel N-heterocyclic carben ligands precursors have been synthesized.
• Novel silver–NHC complexes characterized.
• Novel ruthenium–NHC complexes have been synthesized.
• Ru–NHC performed lovely catalytic activity.
• With this catalyse system ketones reduced to alcohols under mild reaction condition.

The synthesis of highly active ruthenium(II) catalyst based on N-heterocyclic carbene (NHC) bearing alkyl and aryl groups is reported. The complexes are easily handled in very good yields via synthesis of silver–NHC complexes and subsequent reaction with [RuCl2(p-cymene)]2 in dichloromethane (DCM) under N2 condition. All new compounds were characterized by LC-MSMS, elemental analysis, NMR spectroscopy and X-ray diffraction. With the development of a more efficient catalytic system for transfer hydrogenation of aryl ketones and aldehydes in mind, the catalytic performance of the Ru–NHC complexes for transfer hydrogenation was investigated.

NHCs have attracted attention as commonly used ligand for many transition metals. In this study, synthesis and characterisation of imidazol based NHC–ruthenium(II) complexes have been well-defined. These easily prepared air- and moisture-stable imidazol based NHC–ruthenium complexes showed smoothly catalytic activity in the transfer hydrogenation reaction under mild condition.Figure optionsDownload as PowerPoint slide