Characterisation of degradation products in the oxidation of the dodecahydro-7,8-dicarba-nido-undecaborate(1–) ion: a new synthesis of 4,5-dicarba-nido-nonaborane(11)

Abstract

Degradation of aqueous 1 mol dm^–3 K[B₉C₂^7,8H₁₂] by aqueous FeCl₃(1.25 mol dm^–3) yields B₈C₂^5,6H₁₂(33%) as previously reported, together with B₈C₂^5,6H₁₁(OH)(1.6%), B₈C₂^5,6ClH₁₁(0.9%). and B₇C₂^4,5H₁₁(4.2%). The yield of B₇C₂^4,5H₁₁ may be increased substantially by using lower concentrations of reactants (0.1–0.2 mol dm^–3), and this reaction thus provides a simple synthesis of this otherwise highly inaccessible carba-borane. The mass spectrum of B₇C₂^4,5H₁₁ has been obtained. The ¹¹B n.m.r. spectrum of B₈C₂^5,6ClH₁₁, when compared with spectra of the four isomers of B₁₀ClH₁₃, suggests that substitution has occurred at the 10 position, but the position of substitution of the hydroxy-group in B₈C₂^5,6H₁₁(OH) remains uncertain.