Weakly coordinating anions are extremely versatile species for capturing and characterizing cationic intermediates. Among these anions, carboranes and some boranes are known to be the most weakly coordinating anions. In this study, the carboranes and boranes were synthesized in order to use in different fields. B₁₁H₁₄- was synthesized from NaBH₄ and used to synthesize CB₁₁H₁₂-. CB₁₁H₁₂- was synthesized by carbene addition to undecaborate. B₁₁H₁₄- was converted to B₁₀H₁₄ by oxidation and extrusion of one boron vertex. CB₁₁H₁₂- was methylated on boron vertex to get HCB₁₁Me₁₁-. The methylated carborane cages are more hydrophobic and weakly coordinating anions.