Ruthenium Complexes Containing Pyridinyl-Derived Ligands as FLP Catalysts

High Resolution Image Download MS PowerPoint Slide We report the synthesis of ruthenium-based frustrated Lewis pair (FLP) complexes of the general formula [(Mes)Ru(κ 3 N, N ′, N″ - L )][SbF 6 ], where Mes denotes η 6 -1,3,5-C 6 H 3 Me 3 and L corresponds to two different ligands: L1 ( N, N ′-bis(2,6-diisopropylphenyl)- N″ -(2-pyridinylmethyl)guanidinate) in complex 1 and L2 ( N -2-pyridinyl- N -(2-pyridinylmethyl)amidate) in complex 4 . These complexes are obtained from the dimer [{(Mes)RuCl} 2 (μ-Cl) 2 ] in combination with HL1 or HL2 under chloride abstraction and deprotonation conditions. Complexes 1 and 4 undergo reversible heterolytic activation of H 2 to form the corresponding hydrido species [(Mes)RuH(κ 2 N, N ′- HL )][SbF 6 ] ( HL = HL1 for complex 6; HL2 for complex 7 ). The formation of these hydrido complexes is observed in both the hydrodechlorination of chlorinated substrates under H 2 and the base-free dehydrogenation of formic acid, highlighting the reversibility of hydrogen activation within this TMFLP framework. Finally, complexes 1 and 4 act as transition-metal frustrated Lewis pair (TMFLP) hydrogenation catalysts and catalyze the hydrogenation reaction of C═C bonds in acrylates (even in water for 1 ), as well as the C═O bond of 2,2,2-trifluoroacetophenone, and the C═N bond of N -benzylideneaniline.