Electrochemical behaviour and reactivity of [Os(bpy)2(CO)(OTf)] in halogenated solvents

The dimethylaminopyridine (DMAP) promoted reaction between Os(bpy)₂(CO)(OTf)]OTf (where ) and methylene chloride is reported. C-Cl bond breaking of a solvent molecule leads to the formation of the Os(bpy)₂(CO)(Cl)]OTf complex. The reactivity and redox properties of Os(bpy)₂(CO)(OTf)]OTf were investigated by means of room- and low-temperature electrochemical experiments. In CH₂Cl₂, at low temperature, the complex undergoes two 1e electrochemical and chemical reversible reductions (E_rE_r mechanism), but at room temperature a more complex electrochemical mechanism is observed, leading to the electro-synthesis of Os(bpy)₂(CO)(Cl)]OTf via electrochemical reversible and chemical irreversible reduction processes (E_rC_i mechanism). The DMAP nucleophilicity was used to produce the new Os(bpy)₂(CO)(Br)]OTf and Os(bpy)₂(CO)(I)]OTf complexes which have been fully characterized.