The First Example of Electrophilic Mercuration of Icosahedral Dicobaltacarborane 3,6-Cp2-3,6,1,2-Co2C2B8H10

The interaction of equivalent amounts of 3,6-Cp₂-3,6,1,2-Co₂C₂B₈H₁₀ 1 and mercury(II) acetate in boiling CH₂CI₂ followed by treatment with NaCI results in a mixture (1:1.2) of 8- and 9-chloromercury derivatives of dicobaltacarboranes (compounds 2 and 3). The action of excess Hg(OAc)₂ on 1 leads to the tetramercurated compound with substitution in positions 8, 9, 10 and 12 of the carborane icosahedron; the structure of 8-CIHg-3,6-Cp₂-3,6,1,2-Co₂C₂B₈H₉ was determined by an X-ray diffraction study.