Hydrazine nitrosation of a metal-bound nitric oxide: structural evidence for the formation of an ammine complex

Hydrazine nitrosation of Ru(NO)(py(si)S4)]Br.THF (1) (py(si)S4(2-) = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine2-) in methanol/DMF led to the formation of mononuclear ammine complex Ru(NH3)(py(si)S4)] (2) and N2O, whereas the reaction performed in THF/CH2Cl2/toluene afforded thioether-bridged dinuclear ammine complex (NH3)Ru(mu-py(si)S4)Ru(py(si)S4)] (3). Compound 2 dimerizes in solution at room temperature to form 3 and is regenerated upon treatment of 3 with NH3. A plausible mechanism for the hydrazine nitrosation of 1 has been proposed. The reaction of 1 with NH3 or N3- does not lead to a nucleophilic attack at the NO+ ligand but to a deprotonation that yields neutral nitrosyl complex Ru(NO){py(si)S4(H+)}] (4), which is supported by density functional theory calculations.