Syntheses and Reactivity of the Diselenido Molybdenum−Manganese Complex CpMoMn(CO)₅(μ-Se₂)

Reaction of CpMoMn(CO)₈ with elemental selenium and Me₃NO in the absence of light yielded the diselenido complex CpMoMn(CO)₅(μ-Se₂), 2. Compound 2 contains a bridging diselenido ligand lying perpendicular to the Mo−Mn bond, Mo−Mn = 2.8421(10) Å. In the presence of room light, the reaction yielded the tetranuclear metal complex Cp₂Mo₂Mn₂(CO)₇(μ₃-Se)₄, 3 (36% yield), and 2 (7% yield). Compound 2 reacted with ethylene to yield the ethanediselenato complex CpMoMn(CO)₅(μ-SeCH₂CH₂Se), 4, by insertion of ethylene into the Se−Se bond. Compound 2 also reacted with (PPh₃)₂Pt(PhC₂Ph) and CpCo(CO)₂ to yield the complexes CpMoMnPt(PPh₃)₂(CO)₅(μ₃-Se)₂, 5, and Cp₂CoMoMn(CO)₅(μ₃-Se)₂, 6, respectively, by insertion of the metal groupings CpCo and Pt(PPh₃)₂ into the Se−Se bond of 2. The oxo compound Cp₂CoMo(O)Mn(CO)₅(μ₃-Se)₂, 7, was obtained from 6 by decarbonylation at molybdenum by using Me₃NO. The molecular structures of the complexes 2−7 were established by single-crystal X-ray diffraction analyses.