Fluorination of deltahedral closo-borane and -carborane anions with N-fluoro reagents

Abstract

The treatment of cesium salts of CB 11H 12, CB 9H 10, B 12H 2, and B 10H 10 2− with the commercially available N-fluoro reagent 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA) resulted in the formation of fluorinated derivatives of these 10- and 12-vertex borane and carborane anions. This is the first reported use of an N-fluoro reagent to fluorinate BH bonds of any type. The effects of changing the solvent, temperature, and reagent stoichiometry were studied. The derivatives 1-B 10H 9F 2-,2-B 10H 9 F 2, and 1,10-B 10H 8F 2 2 are the first fluorinated derivatives of the parent B 10H 10 2 cluster. For the other three parent anions, reactions with F-TEDA resulted in a higher degree of fluorination than reactions with liquid anhydrous hydrogen fluoride (LAHF) at the same temperature. However, F-TEDA was found to be less regioselective than LAHF for BH → BF transformations.