Structural Characterization of Novel Ionic Materials Incorporating the Bis(trifluoromethanesulfonyl)amide Anion

A range of low melting salts of the bis(trifluoromethanesulfonyl)amide (TFSA) anion with
hindered organic cations (N-methyl-1-methylpyrrolinium, N,N-dimethylpyrrolidinium, N,N,N,-trimethylammonium, and N,N,N,N-tetrakis(n-propyl)ammonium) have been crystallized.
Single-crystal X-ray diffraction data show these materials to consist of discrete ions with
only weak C−H···O (or for Me3NH N−H···O) contacts between the constituent atoms of the
cations and anions close to the limits of van der Waals separations. Consequently, the
observed physical properties of these materials presumably result from the diffuse negative
charge on the TFSA anion and inefficient packing of these large and irregularly shaped
ions.