A Return to the Plesek Reaction and Some Useful Variations. Carbon-Substituted Methyl and Phenyl Derivatives of 5,6-Dicarba-nido-decaborane(12), nido-5,6-C2B8H12

Abstract

A modification of the Plesek reaction has been employed to improve the yield in the synthesis of the parent nido ten-vertex dicarbaborane 5,6-C2B8H12, and to synthesize some of its 5- and 6-substituted derivatives. The method is based on the oxidation of the anions [7,8-R1R2-nido-5,6-C2B9H10]- with acidic aqueous of [Fe(H2O)6]Cl3 to produce the series of substituted dicarbaboranes 5,6-R1R2-nido-5,6-C2B8H10, where R1, R2 = H, H; H, Me; Me, H; Me, Me; H, Ph; Ph, H, and Ph, Ph. The characteristic reaction mode is an oxidative elimination of one boron vertex that is adjacent to the carbon vertex in the open pentagonal face of the starting eleven-vertex nido dicarbaborane anion. The products are characterized by mass spectrometry and 1H and 11B NMR spectroscopy including [11B-11B]-COSY and 1H-{11B(selective)} measurements that permit complete assignments of all the observed resonances to individual cluster {BH} units.