Simple Synthesis, Halogenation, and Rearrangement of <i>closo</i>-1,6‑C₂B₈H₁₀

Room-temperature reaction between nido-5,6-C2B8H12 (1) and elemental iodine in the presence of triethylamine in CH2Cl2 gave the closo-1,6-C2B8H10 (2) dicarbaborane in 85% yield. All the electrophilic halogenation reactions of 2 led exclusively to B(8)-substitution to get a series of 8-X-closo-1,6-C2B8H9 (8X-2) derivatives (where X = Cl, Br, and I). Thermal rearrangements of 2 and 8X-2 at ∼500–600 °C produced closo-1,10-C2B8H10 (3) and a series of halo derivatives 2-X-closo-1,10-C2B8H9 (2X-3), respectively. All the compounds isolated have been characterized by multinuclear (11B, 1H, and 13C) NMR spectroscopy, mass spectrometry, and elemental analyses, and the structure of 8Br-2 was established by X-ray diffraction study.