ABSTRACT
Weakly coordinating anions (WCAs) facilitate the stabilization and isolation of highly reactive and almost "naked" cations. Alkoxyaluminate-based WCAs such as [Al(OC(CF3)3)4]- ([pf]-) 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 [pf]- anion or even to abstract an alkoxy ligand. The novel WCA [Al(OC10F15)4]- ([pfAd]-; OC10F15 = 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 [pfAd]- anion was generated by the reaction of the highly acidic alcohol perfluoro-1-adamantanol C10F15OH with LiAlH4 in o-DFB. Li[pfAd] could not be synthesized free of impurities (and still contains unreacted alcohol). Yet, starting from contaminated Li[pfAd], the very useful pure salts Ag[pfAd], [Ph3C][pfAd] and [H(OEt2)2][pfAd] could be synthesized. The salts were characterized by NMR spectroscopy, single-crystal X-ray diffraction and IR spectroscopy. Additionally, [NO][pfAd] could be synthesized containing alcohol impurities but nonetheless enabled the synthesis of the salt P9+[pfAd]-. The synthesis of Tl[pfAd] in a mixture of H2O/acetone/o-DFB demonstrated the water stability of the [pfAd]- anion.
