Building blocks for the chemistry of perfluorinated alkoxyaluminates [Al{OC(CF3)3}4]−: simplified preparation and characterization of Li+–Cs+, Ag+, NH4+, N2H5+ and N2H7+ salts

Abstract

Advanced weakly coordinating anions (WCAs) significantly facilitate synthesis of various exotic chemical compounds and novel, potentially useful materials. One of such anions – [Al{OC(CF₃)₃}₄]⁻, denoted [Al(OR^F)₄]⁻, appears particularly convenient, as it can be easily prepared from the commercially available alanates and HOC(CF₃)₃. Here we present a thorough characterization of a series of solvent-free M[Al(OR^F)₄] salts, M = Li–Cs, Ag, NH₄, N₂H₅ and N₂H₇, and related compounds of monovalent cations, which are crucial starting materials for further work with these species. Notably, the corresponding synthetic protocols are updated by an improved method for fast, facile and easily scalable synthesis of Li[Al(OR^F)₄], which remains the most useful primary source of the anion. The physico-chemical properties of these salts including crystal structures, thermal stability by TG/DSC, vibrational spectra as well as solubility are discussed in a systematic fashion.