| Sumario: | Pyridyl-thiourea complexes of formula [(Cym)MCl(κ2Npy,S-H2NNS)][SbF6] (Cym = η6-p-MeC6H4iPr; H2NNS = N-(p-tolyl)-N′-(2-pyridylmethyl)thiourea); M = Ru (1), Os (2)) were synthesized by reacting the corresponding metal dimers [{(Cym)MCl}2(μ-Cl)2] with H2NNS in the presence of NaSbF6. Subsequent chloride abstraction with AgSbF6, followed by NH deprotonation using NaHCO3, afforded the cationic complexes [(Cym)M(κ3Npy,Namide,S-HNNS)][SbF6] (M = Ru (5a), (5c); M = Os (6a, 6c)) and [(Cym)M(κ2Namide,S-HNNS)][SbF6] (M = Ru (5b); M = Os (6b)). The proposed structures for the prepared compounds are based on NMR data. Complexes 5a, 5b, and 6a, 6b evolve to the thermodynamically more stable species 5c and 6c, respectively, in which the deprotonated ligand HNNS adopts a κ3Npy,Namide,S coordination mode. Complexes 5c and 6c activate H2, behaving as frustrated Lewis pair (FLP) species, and catalyze (5c and/or 6c) the hydrogenation of polar multiple bonds, including the C=N bonds of N-benzylideneaniline and quinoline, the C=C bond of methyl acrylate, and the C=O bond of 2,2,2-trifluoroacetophenone.
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