Synthesis and transfer hydrogenation catalysis of chelating triazolylidene ruthenium(II) complexes: Effect of the pendant arm, p-cymene, acetonitrile and butadienesulfonyl co-ligands

Abstract

Five ruthenium(II) complexes containing chelating triazolylidene ligands, varying on the allyl or picolyl pendant arm, and p-cymene, MeCN and/or butadienesulfonyl co-ligands have been synthesised and characterised: [(p-cymene)Ru(TzAllylMe)Cl]PF6 (1), [(p-cymene)Ru(TzPyMe)Cl](OTf) (2), [Ru(TzAllylMe)(CH3CN)4](PF6)2 (4), [Ru(TzPyMe)(CH3CN)4](OTf)2 (5) and [Ru(TzPyMe)(η1-SO2CHCHCHCH2)(CH3CN)3]OTf (7), TzRMe = 1-R-4-butyl-1,2,3-triazolylidene (R = allyl or 2-picolyl, TzAllylMe or TzPyMe respectively). The effect of the chelating arm and co-ligands on the ruthenium centre has been evaluated by screening the catalytic activity of the complexes in the transfer hydrogenation of benzophenone.