We report the synthesis of ruthenium-based frustrated Lewis pair (FLP) complexes of the general formula (Mes) Ru (κ3N, N′, N″-L) SbF6, where Mes denotes η6-1, 3, 5-C6H3Me3 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) RuCl2 (μ-Cl) 2 in combination with HL1 or HL2 under chloride abstraction and deprotonation conditions. Complexes 1 and 4 undergo reversible heterolytic activation of H2 to form the corresponding hydrido species (Mes) RuH (κ2N, N′-HL) SbF6 (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 H2 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.
Grasa et al. (Thu,) studied this question.