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

Ru(0) complexes of bis(imino)pyridine ligands, [η2-N3]Ru(η6-Ar) and {[N3]Ru}2(μ-N2), where Ar = C6H6 or C6H5Me and [N3] = 2,6-(MesNCMe)2C5H3N, react with N-heterocyclic silicon(IV) compounds to yield Ru(II) silylene complexes of the type [N3]Ru(X)(Cl){Si(NN)} (X = H, Cl, and Si(NN) = N,N‘-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, [N3]Ru(N2){Si(NN)}, which also contains a terminal dinitrogen ligand.