Versatile coordination of 2-pyridinetetramethyldisilazane at ruthenium: Ru(II) vs Ru(IV) as evidenced by NMR, X-ray, neutron, and DFT studies.

The novel disilazane compound 2-pyridinetetramethyldisilazane (1) has been synthesized. The competition between N-pyridine coordination and Si−H bond activation was studied through its reactivity with two ruthenium complexes. The reaction between 1 and RuH2(H2)2(PCy3)2 led to the isolation of the new complex RuH2{(η2-HSiMe2)N(κN-C5H4N)(SiMe2H)}(PCy3)2 (2) resulting from the loss of two dihydrogen ligands and coordination of 1 to the ruthenium center via a κ2N,(η2-Si−H) mode. Complex 2 has been characterized by multinuclear NMR experiments (1H, 31P, 13C, 29Si), X-ray diffraction and DFT studies. In particular, the HMBC 29Si−1H spectrum supports the presence of two different silicon environments: one Si−H bond is dangling, whereas the other one is η2-coordinated to the ruthenium with a JSiH value of 50 Hz. DFT calculations (B3PW91) were also carried out to evaluate the stability of the agostic species versus a formulation corresponding to a bis(σ-Si−H) isomer and confirmed that N-coordination overcomes any ...