Synthesis of new fluoro derivatives of o-carborane [3-F-7,8-C₂B₉H₁₁]⁻, 3,6-F₂-1,2-C₂B₁₀H₁₀, and [6,6′-F₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻

The 3,6-difluoro derivative of ortho-carborane 3,6-F₂-1,2-C₂B₁₀H₁₀ was obtained by a triple sequence of deboronation and BF-insertion reactions. 3-Fluoro and, especially, 3,6-difluoro derivatives of ortho-carborane were found to have an increased propensity to deboronation with elimination of the BF group under the action of even weak nucleophilic agents, which, apparently, is explained by a reduced electron density on the boron atoms bearing fluorine atoms. The 6,6′-difluoro derivative of cobalt bis(dicarbollide) [6,6′-F₂-3,3′-Co(1,2-C₂B₉H₁₀)₂]⁻ was obtained from 3-fluoro-nido-carborane [3-F-7,8-C₂B₉H₁₁]⁻. The new fluoro derivatives of ortho-carborane were characterized by multinuclear NMR spectroscopy.