The reaction of samarium(II) with manganese carbonyl: unexpected conversion of CO to formate. X-ray crystal structures of [Sm(TpMe2)2]Mn(CO)5 and {[Sm(TpMe2)2]2(μ-HCO2)}Mn(CO)5 (TpMe2=HB(3,5-dimethylpyrazolyl)

The reaction of [Sm(TpMe2)2] with Mn2CO10 results in the reductive cleavage of the Mn–Mn bond and the formation of the salt [Sm(TpMe2)2]Mn(CO)5 which has been characterized by X-ray diffraction (TpMe2=HB(3,5-dimethylpyrazolyl)3). In addition a second product, [(TpMe2)2Sm(μ-O2CH)Sm(TpMe2)2]Mn(CO)5, was isolated and characterized crystallographically. Two mechanisms for the formation of this complex are proposed.