Diruthenium( ii )–NNN pincer complex catalysts for transfer hydrogenation of ketones

. Compared with the corresponding mononuclear Ru(ii)-NNN pincer complexes, the bimetallic complexes could be applied at concentrations as low as 0.03 mol% Ru and demonstrated remarkably enhanced catalytic activity in the transfer hydrogenation reactions of ketones. The high catalytic activity of the diruthenium(ii) complexes is attributed to the excellent stability and possible cooperativity of the two coordinated Ru(ii) metal centers through the π linker. The present synthetic methodology has established an applicable strategy to construct highly active bimetallic NNN pincer complex catalysts.