Synthesis and Structure of Ruthenium−Silylene Complexes:  Activation of Si−Cl Bonds in N-Heterocyclic Silanes

Ru(0) complexes of bis(imino)pyridine ligands, [η<sup>2</sup>-N<sub>3</sub>]Ru(η<sup>6</sup>-Ar) and {[N<sub>3</sub>]Ru}<sub>2</sub>(μ-N<sub>2</sub>), where Ar = C<sub>6</sub>H<sub>6</sub> or C<sub>6</sub>H<sub>5</sub>Me and [N<sub>3</sub>] = 2,6-(MesNCMe)<sub>2</sub>C<sub>5</sub>H<sub>3</sub>N, react with N-heterocyclic silicon(IV) compounds to yield Ru(II) silylene complexes of the type [N<sub>3</sub>]Ru(X)(Cl){Si(NN)} (X = H, Cl, and Si(NN) = <i>N</i>,<i>N</i>‘-bis(neopentyl)-1,2-phenylenedi(amino)silylene). The activation of two groups on the silane occurs in a stepwise fashion:  initial oxidative addition of a Si−X bond, followed by 1,2-migration (α-elimination) of the Si−Cl group to the metal. Reversible dissociation from the Ru(II) center leads to free silylene, which can be preferentially trapped with Ru(0) complexes to generate a zero-valent silylene complex, [N<sub>3</sub>]Ru(N<sub>2</sub>){Si(NN)}, which also contains a terminal dinitrogen ligand.