The perfluoroadamantoxy aluminate as an ideal weakly coordinating anion? - synthesis and first applications.

Weakly coordinating anions (WCAs) facilitate the stabilization and isolation of highly reactive and almost "naked" cations. Alkoxyaluminate-based WCAs such as [Al(OC(CF))] ([]) are widely used due to their synthetic accessibility and their high stability. However, small cations are still able to coordinate the oxygen atoms of the [] anion or even to abstract an alkoxy ligand. The novel WCA [Al(OCF)] ([]; OCF = perfluoro-1-adamantoxy) is characterized by a very rigid core framework, thus indicating a higher stability towards fluoride-ion abstraction (DFT calculations) and providing hope to generate less disordered crystal structures. The [] anion was generated by the reaction of the highly acidic alcohol perfluoro-1-adamantanol CFOH with LiAlH in -DFB. Li[] could not be synthesized free of impurities (and still contains unreacted alcohol). Yet, starting from contaminated Li[], the very useful pure salts Ag[], [PhC][] and [H(OEt)][] could be synthesized. The salts were characterized by NMR spectroscopy, single-crystal X-ray diffraction and IR spectroscopy. Additionally, [NO][] could be synthesized containing alcohol impurities but nonetheless enabled the synthesis of the salt P[]. The synthesis of Tl[] in a mixture of HO/acetone/-DFB demonstrated the water stability of the [] anion.