Abstract
The synthesis of half‐sandwich transition‐metal complexes containing the Cab^N^ and Cab^N,S^ chelate ligands (HCab^N^=HC~2~B~10~H~10~CH~2~C~5~H~4~N (1), LiCab^N,S^=LiSC~2~B~10~H~10~CH~2~C~5~H~4~N (4)) is described. Compounds 1 and 4 were treated with chloride‐bridged dimers [{Ir(Cp*)Cl~2~}~2~] (Cp*=η^5^‐C~5~Me~5~), [{Ru(p‐cymene)Cl~2~}~2~] and [{Rh(Cp*)Cl~2~}~2~] to give half‐sandwich complexes [Ir(Cp*)Cl(Cab^N^)] (2), [Ru(p‐cymene)Cl(Cab^N^)] (3), and [Rh(Cp*)Cl(Cab^N,S^)] (5), respectively. Addition reaction of LiCab^S^ (Cab^S^=SC~2~(H)B~10~H~10~) to the rhodium complex 5 yields [Rh(Cp*)(Cab^S^)(Cab^N,S^)] (6). All the complexes were characterized by IR and NMR spectroscopy, and by elemental analysis. In addition, X‐ray structure analyses were performed on complexes 2, 3, 5, and 6, in which the potential C,N‐ and N,S‐chelate ligands were found to coordinate in a bidentate mode. The carborane complex 2 shows catalytic activities up to 3.7×10^5^ g PE mol^−1^ Ir h^−1^ for the polymerization of ethylene in the presence of methylaluminoxane (MAO) as cocatalyst. The polymer obtained from this homogeneous catalytic reaction has a spherical morphology. Catalytic activities and the molecular weight of polyethylene have been investigated for various reaction conditions.