This project investigates fluorinated and other halogenated carba-closo-borate anions and other closo-boron clusters with functional groups. The aim of this project is to make polyfluorinated, functionalized boron clusters available as building blocks for different applications. For this purpose (selective) synthetic routes have to be developed and the influence of the fluorine substituents on the properties of the clusters and the functional groups has to be examined.
The fluorinated clusters are synthesized by reacting the non-fluorinated starting materials with elemental fluorine in anhydrous hydrogen fluoride. These polyfluorinated boron clusters show an unexpected high chemical reactivity, which differs significantly from the chemically extremely inert, weakly coordinating anions [1-R-closo-1-CB11F11]− (R = H, alkyl, F). One example is the carbon extrusion respectively cluster contraction reaction of the [1-H2N-closo-CB11F11]− anion to the closo-undecaborate dianion [3-NC-closo-B11F10]2− shown in the following scheme:
These new anionic highly fluorinated boron clusters are intended to serve as novel synthesis building blocks and ligands with a Teflon-like surface, resulting in applications in the fields of medicine, catalysis and new materials (polymers, ionomers, ionic liquids).