Step-by-step introduction of silazane moieties at ruthenium: different extents of Ru−H−Si bond activation

he coordination of pyridine-2-amino(methyl)dimethylsilane ligands to ruthenium has afforded access to a family of novel complexes that display multicenter Ru-H-Si interactions according to the number of incorporated ligands. The new complexes Ru[kappa-Si,N-(SiMe2)N(Me)(C5H4N)](eta(4)-C8H12)(eta(3)-C8H11) (1), Ru-2(mu-H)(2)(H)(2)[kappa-Si,N-(SiMe2)N(Me)(C3H4N)](4) (2), and Ru(H)[kappa-Si,N-(SiMe2)N(Me)(C5H4N)](3) (3) were isolated and fully characterized. The complexes exhibit different degrees of Si H activation: complete Si H cleavage, secondary interactions between the atoms (SISHA), and re-Si H coordination. Reversible protonation of 3 leading to the cationic complex [RuH{(t/2-HSiMe2)N(Me)kappa-N-(C3H4N)){kappa-Si,N-(SiMe2)N(Me)(C5H4N)}(2)](+)[BAr4F](-) (5) was also demonstrated. The coordination modes in these systems were carefully studied with a combination of X-ray and neutron diffraction analysis, DFT geometry optimization, and multinuclear NMR spectroscopy.