Samarocene oxide: from an undesired decomposition product to a new reagent

Abstract

Samarocene oxide [Cp*₂Sm-O-SmCp*₂] is mostly considered as an undesired decomposition product of the well-established but highly air-sensitive samarocene, [Cp*₂Sm(thf)₂]. [Cp*₂Sm-O-SmCp*₂] is often formed by accidental exposure of [Cp*₂Sm(thf)₂] to air or wet solvents. We show here that [Cp*₂Sm-O-SmCp*₂] acts as a mild oxide base and thus is a valuable synthetic equivalent for “O²⁻”. The reaction of [Cp*₂Sm-O-SmCp*₂] with the inorganic and organic anhydrides COS, CS₂, SO₂, SO₃, Re₂O₇, and (PhC(O))₂O at room temperature resulted in each case in an O²⁻ insertion. The corresponding products were isolated as their samarium complexes.