Sulfur and oxygen functionalized cyclopentadienyl half-sandwich cobalt complexes with 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolato ligands

Sulfur and oxygen functionalized cyclopentandienyl half-sandwich cobalt dicarbonyl complexes η⁵-C₅H₄(CH₂)₂SCH₂CH₃]Co(CO)₂ (3) and η⁵-C₅H₄(CH₂)₂OCH₃]Co(CO)₂ (7) were prepared. Oxidation of 3 or 7 with I₂ led to formation of 18-electron complexes η⁵-C₅H₄(CH₂)₂SCH₂CH₃]CoI₂ (4) and η⁵-C₅H₄(CH₂)₂OCH₃]Co(CO)I₂ (8). The reactions of diiodide complex (4) with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolates (THF)₃LiE₂C₂B₁₀H₁₀Li(THF)]₂ E=S (1a), Se (1b)] afforded 18-electron mononuclear complexes η⁵-C₅H₄(CH₂)₂SCH₂CH₃]Co(E₂C₂B₁₀H₁₀) E=S (5a), Se (5b)] in which sulfur atoms of side-chain were attached via an intramolecular coordination. Complex 7 reacted with 1a and 1b to give the binuclear complexes {η⁵-C₅H₄(CH₂)₂OCH₃]Co(E₂C₂B₁₀H₁₀)}₂ E=S (10a), Se (10b)]. The molecular structures of 5a and 10b were determined by X-ray crystallographic analysis. According to the X-ray structure analyses, 10b contains two o-carborane diselenolate bridges, and each Cp^′Co fragment is attached to one terminal and two bridging selenolato ligands. The central Co₂Se₂ four-membered ring is planar, and the direct metal-metal interaction is absent.