Polyhedral monocarbaborane chemistry: positional isomerism within the 10-vertex monocarbaborane cluster: synthesis and characterisation of the [2-Ph-closo-2-CB9H9]− anion

Positional isomerism of cluster carbon in monocarbaborane chemistry is rare. Oxidation of the [6-Ph-nido-6-CB9H11]− anion or the unsubstituted [arachno-6-CB9H14]− anion with elemental I2 in alkaline solution gives a quantitative conversion to the previously uncharacterised [2-R-closo-2-CB9H9]− anions, where R is Ph or H, respectively; these anions isomerise quantitatively under strong heating to give their previously established [1-R-closo-1-CB9H9]− isomers.