Ionic liquids and solids with paramagnetic anions

Abstract

Four paramagnetic ionic compounds have been prepared and their magnetic, structural and thermal properties have been investigated. The four compounds are methylbutylpyrrolidinium tetrachloroferrate(III) ([Pyrr₁₄]⁺/[FeCl₄]⁻), methyltributylammonium tetrachloroferrate(III) ([N₁₄₄₄]⁺/[FeCl₄]⁻), butylmethylimidazolium tetrachloroferrate(III) ([bmim]⁺/[FeCl₄]⁻) and tetrabutylammonium bromotrichloroferrate(III) ([N₄₄₄₄]⁺/[FeBrCl₃]⁻). Temperature-dependent studies of their magnetic behaviors show that all four compounds are paramagnetic at ambient temperatures. Glass transitions are observed for only two of the four compounds, [Pyrr₁₄]⁺/[FeCl₄]⁻ and [bmim]⁺/[FeCl₄]⁻. Crystal structures for [Pyrr₁₄]⁺/[FeCl₄]⁻ and [N₁₄₄₄]⁺/[FeCl₄]⁻ are compared with the previously reported [N₄₄₄₄]⁺/[FeBrCl₃]⁻.