Reaction of 13-Vertex Carborane μ‑1,2-(CH₂)₄‑1,2‑C₂B₁₁H₁₁ with Nucleophiles: Linkage Effect on Product Formation

The length of C,C′-linkage has a great influence on the reactivity of 13-vertex carboranes. Reaction of 1,2-(CH₂)₄-1,2-C₂B₁₁H₁₁ (1a) with Et₂NH gave a 1:1 adduct nido-7-NEt₂H-μ-1,3-(CH₂)₄-1,3-C₂B₁₁H₁₁ (2). Compound 1a reacted with Me₂NLi or Et₂NLi to afford nido-[9-Nu-μ-7,8,10-(CH₂)₄CCH-B₁₁H₁₀]⁻ (Nu = NMe₂, [3]⁻; Nu = NEt₂, [4]⁻). Complex [4]⁻ was also obtained by deprotonation of 2. Treatment of 1a with MeOH/base generated nido-[3-OMe-μ-1,2-(CH₂)₄-1,2-C₂B₁₁H₁₁]⁻ ([5]⁻) at room temperature, which was converted to nido-[μ-7,8-(CH₂)₄CHB­(OMe)₂-7-CB₁₀H₁₁]⁻ ([6]⁻) upon heating in the presence of Et₃N. Complex [6]⁻ was oxidized by H₂O₂ to the corresponding alcohol [μ-7,8-(CH₂)₄CHOH-7-CB₁₀H₁₁]⁻ ([7]⁻) or hydrolyzed to the boronic acid [μ-7,8-(CH₂)₄CHB­(OH)₂-7-CB₁₀H₁₁]⁻ ([8]⁻). Reaction of 1a with (4-MeC₆H₄)­SNa produced a CB₁₁^– anion closo-[μ-1,2-(CH₂)₄CHS­(4-MeC₆H₄)-1-CB₁₁H₁₀]⁻ ([9]⁻). The above complexes were fully characterized by ¹H, ¹³C, and ¹¹B NMR spectroscopic data and elemental analyses. Molecular structures of 1–[7]⁻ and [9]⁻ were further confirmed by single-crystal X-ray analyses.