Collect. Czech. Chem. Commun. 1997, 62, 1263-1272

Phenyl-Induced 3,1,11-Rearrangement in the Synthesis of Mixed Pyrrolyl/Dicarbollide Cobaltadicarbaboranes

Josep Bertrana, Clara Viñasa, Sílvia Gomeza, Mouad Lamrania, Francesc Teixidora, Reijo Sillanpääb and Raikko Kivekäsc

a Institut de Ciència de Materials de Barcelona, Campus de la U.A.B., E-08193 Bellaterra, Spain
b Department of Chemistry, University of Turku, FIN-20014 Turku, Finland
c Department of Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland


Mixed pyrrolide cobaltadicarbollides have been prepared from the reaction involving potassium pyrrolide, anhydrous CoCl2 and the [7,8-(C6H5)2-nido-7,8-C2B9H10]- anion in dimethoxyethane. An alternative and higher-yield route consists in the reaction between 1,2-(C6H5)2-closo-1,2-C2B10H10 and potassium pyrrolide in the presence of anhydrous CoCl2. As confirmed by the X-ray diffraction analysis of [3-(η5-NC4H4)-1,11-(C6H5)2-closo-3,1,11-CoC2B9H9], the phenyl rings were found to enhance the rearrangement of the metallacarborane cluster carbons to produce the 3,1,11-isomer instead of the expected 3,1,2-derivative. As suggested by 1H and 13C NMR spectroscopy, the electron-withdrawing properties and steric requirements of the phenyl rings facilitate the rearrangement.

Keywords: Carboranes; Pyrrolide; Cobaltacarboranes.