Nickel−Manganese Sulfido Carbonyl Cluster Complexes. Synthesis, Structure, and Properties of the Unusual Paramagnetic Complexes Cp₂Ni₂Mn(CO)₃(μ₃-E)₂, E = S, Se

The reaction of Mn2(CO)7(μ-S2) with [CpNi(CO)]2 yielded the paramagnetic new compound Cp2Ni2Mn(CO)3(μ3-S)2 (1) and a new hexanuclear metal product Cp2Ni2Mn4(CO)14(μ6-S2)(μ3-S)2 (2). Structurally, compound 1 contains two triply bridging sulfido ligands on opposite sides of an open Ni2Mn triangular cluster. EPR and temperature-dependent magnetic susceptibility measurements of 1 show that it contains one unpaired electron. The electronic structure of 1 was determined by Fenske−Hall molecular orbital calculations which show that the unpaired electron occupies a low lying antibonding orbital delocalized unequally across the three metal atoms. The selenium homologue Cp2Ni2Mn(CO)3(μ3-Se)2 (3) was obtained from the reaction of a mixture of Mn2(CO)10 and [CpNi(CO)]2 with elemental selenium and Me3NO·2H2O. It also has one unpaired electron. Compound 1 reacted with elemental sulfur to yield the dinickeldimanganese compound, Cp2Ni2Mn2(CO)6(μ4-S2)(μ4-S5), 4, which can also be made from the reaction of Mn2(CO)7(μ-S2) with [CpNi(CO)]2 and sulfur. Compound 4 was converted back to 1 by sulfur abstraction using PPh3. The reaction of Mn2(CO)10 with [CpNi(CO)]2 in the presence of thiirane yielded the ethanedithiolato compound CpNiMn(CO)3(μ-SCH2CH2S) (5), which was also obtained from the reaction of Mn4(CO)15(μ3-S2)(μ4-S2) with [CpNi(CO)]2 in the presence of thiirane. Compound 5 reacted with additional quantities of thiirane to yield the new compound CpNiMn(CO)3[μ-S(CH2CH2S)2], 6, which contains a 3-thiapentanedithiolato ligand that bridges the two metal atoms. Compound 6 was also obtained from the reaction of Mn2(CO)10 with [CpNi(CO)]2 and thiirane. The molecular structures of the new compounds 1−6 were established by single-crystal X-ray diffraction analyses.