Hydrazine Nitrosation of a Metal-Bound Nitric Oxide: Structural Evidence for the Formation of an Ammine Complex

Hydrazine nitrosation of [Ru(NO)(pysiS4)]Br·THF (1) (pysiS42- = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine2-) in methanol/DMF led to the formation of mononuclear ammine complex [Ru(NH3)(pysiS4)] (2) and N2O,
whereas the reaction performed in THF/CH2Cl2/toluene afforded thioether-bridged dinuclear ammine complex [(NH3)Ru(μ-pysiS4)Ru(pysiS4)] (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){pysiS4(H+)}] (4), which is supported by density functional theory calculations.