Triflyloxy-substituted carboranes as useful weakly coordinating anions

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Supramolecular Chemistry

Background:

• Carborane anions are versatile boron clusters with unique electronic properties.
• Developing new carborane derivatives is crucial for advancing coordination chemistry and catalysis.
• Triflyloxy (trifluoromethanesulfonyloxy) groups offer tunable electronic and steric properties.

Purpose of the Study:

• To synthesize and characterize novel carborane anions featuring triflyloxy substituents.
• To investigate the stability and reactivity of these new carborane derivatives, particularly their halogenation.
• To evaluate the utility of a specific triflyloxy carborane derivative as a weakly coordinating anion.

Main Methods:

• Synthesis of carborane precursors.
• Introduction of triflyloxy substituents onto the carborane cage.
• Halogenation reactions (bromination and chlorination) under controlled conditions.
• Spectroscopic characterization (NMR, Mass Spectrometry) of the resulting compounds.
• Evaluation of anion coordinating ability in relevant chemical systems.

Main Results:

• Successful synthesis of carborane anions with one and three triflyloxy substituents.
• Demonstration of selective halogenation (pentabromo and decachloro derivatives) while preserving the B-OTf bond.
• Characterization of the novel halogenated and triflyloxy-substituted carborane anions.
• Experimental evidence supporting the use of [HCB11Cl10OTf](-) as a weakly coordinating anion.

Conclusions:

• Novel triflyloxy-substituted carborane anions have been successfully prepared.
• The B-OTf linkage exhibits robustness towards halogenation, enabling further functionalization.
• [HCB11Cl10OTf](-) is a viable weakly coordinating anion, expanding the toolkit for coordination chemistry.