“Anti-Crown” Chemistry: Synthesis of [9]Mercuracarborand-3 and the Crystal Structure of Its Acetonitrile Complexes

The reaction of mercuric acetate with closo-1,2-Li₂-l,2-C₂B₁₀H₁₀ yielded [9]mercuracarborand-3, (C₂B₁₀H₁₀Hg)₃ (1), in 60% yield. Compound 1 was characterized by multinuclear NMR spectroscopy and its chloride ion complex, 1·Cl⁻, by negative ion FAB mass spectroscopy. The structure of 1 was determined by X-ray crystallography. 1 crystallized from acetonitrile in the monoclinic space group P2₁/c with a = 13.358 (2), b = 26.846 (4), and c = 20.375 Å, Å = 109.694 (5)°, V = 7909 ų, and Z = 4. Data were collected on a Picker FACS-1 diffractometer, using Mo Kβ radiation, to a maximum 28 = 45°, giving 10 348 unique reflections, and the structure was solved by heavy atom methods. The final discrepancy index was R = 0.044, R_w = 0.049 for 5193 independent reflections with I > 3σ(I). The chloride ion complex of 1,1·ClLi, was formed upon treatment of 1 with LiCl. The complexation behavior of 1 in acetone was studied by ¹⁹⁹Hg NMR spectroscopy.