Crystallographic evidence for the diene character of C2B10H10C4H4(‘benzocarbonae’) and a Diels–Alder reaction of its anionic nido-analogue, [C2B9H10C4H4]–: crystal structures of C2B10H10C4H4 and C2B10H10C4H6

Abstract

Single-crystal X-ray diffraction studies on [C₂B₁₀H₁₀C₄H₄](‘benezocarborane’) and C₂B₁₀H₁₀C₄H₆(‘dihydrobenzocarborane’) show that the C₆ rings of each posses localised double bonds and this has been confirmed by bond-order calculations: the nido-anion. [C₂B₉H₁₀C₄H₄]^– synthesised from C₂B₁₀H₁₀C₄H₄, with maleic anhydride forms a Diels-Alder adduct.