Synthesis, structure and reactivity of 1-(α-C,α′-halo-o-xylyl)-2-trialkylsilyl-1,2-dicarbaboranes

Abstract

Treating Li[^tBuMe₂Si-1,2-C₂B₁₀H₁₀] with excess α,α′-dihalo-o-xylenes, 1,2-C₆H₄(CH₂X)₂ (X = Br, Cl), generates only 1-(α-C,α′-halo-o-xylyl)-2-(tert-butyldimethylsilyl)-1,2-dicarba-closo-dodecaboranes, 1-{o-(XCH₂C₆H₄CH₂)}-2-^tBuMe₂Si-1,2-C₂B₁₀H₁₀ (X = Cl 1a, Br 1b). The structures of both 1a and 1b were determined by single crystal X-ray diffraction. Reaction of either 1a or 1b with ⁿBuLi or MeLi affords the substituted ethane, (2-^tBuMe₂Si-1,2-C₂B₁₀H₁₀-1-o-CH₂C₆H₄)₂C₂H₄2 whereas reaction with ^tBuHNLi affords the substituted ethene (2-^tBuMe₂Si-1,2-C₂B₁₀H₁₀-1-o-CH₂C₆H₄)₂C₂H₂3; both structures were confirmed by X-ray diffraction. Cleavage of the carborane–silicon bond in 1a or 1b by Bu₄NF gives dihydronaphthocarborane, 4, which has been structurally characterised.