Efficient access to amides of the carborane carboxylic acid [1-(COOH)–CB11H11]−

Abstract

The preparation of the carborane acid chloride [1-(COCl)–CB₁₁H₁₁]⁻ from the carboxylic acid [1-(COOH)–CB₁₁H₁₁]⁻ is reported. This acid chloride exhibits remarkable inertness towards moisture and can be stored under ambient conditions for several months. Reaction with amines affords secondary and tertiary carborane amides [1-(CONR¹R²)–CB₁₁H₁₁]⁻ in moderate to high yields under mild conditions. Two of the amide products were characterized by X-ray crystallography in addition to spectroscopic analysis. Preliminary studies show that the amides can be reduced to the corresponding amines and that the acid chloride has the potential to serve as a starting material for carborane ester formation.