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

Reaction of CpMoMn(CO)8 with elemental selenium and Me3NO in the absence of light yielded the diselenido complex CpMoMn(CO)5((mu)-Se2), 2. Compound 2 contains a bridging diselenido ligand lying perpendicular to the Mo-Mn bond, Mo-Mn = 2.8421(10) (angstrom). In the presence of room light, the reaction yielded the tetranuclear metal complex Cp2Mo2Mn2(CO)7(3-Se)4, 3 (36% yield), and 2 (7% yield). Compound 2 reacted with ethylene to yield the ethanediselenato complex CpMoMn(CO)5((mu)-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((mu)3-Se)2, 5, and Cp2CoMoMn(CO)5((mu)3-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((mu)3-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.