Synthesis of magnesium complexes of ionic liquids with highly coordinating anions

Abstract

Magnesium(II) complexes, [Mg²⁺(hfac⁻)₃][Cation⁺], were prepared as solids from hydrophobic hexafluoroacetylacetonate ionic liquids ([Cation⁺][hfac⁻] ILs) and Mg(Tf₂N)₂. 1-Butyl-3-methylimidazolium ([C₄mim]), N-butylpyridinium ([C₄Pyr]), N-butyl-N-methylpiperidinium ([C₄Pip]), N-hexyl-N-methylmorpholinium ([C₆Morp]) and N-butyl-N-methylpyrrolidinium ([C₄pyrr]) were used as cationic cores. The [C₄Pip][hfac], [C₄Pyr][hfac] and [C₆Morp][hfac] ILs were prepared for the first time. New Mg(II) complexes, [C₄mim][Mg(hfac)₃], [C₄Pip][Mg(hfac)₃], [C₄Pyr][Mg(hfac)₃], [C₆Morp][Mg(hfac)₃] and [C₄Pyrr][Mg(hfac)₃], were obtained from the [hfac] based ILs. The crystal structures of the novel Mg(II) complexes show the coordination of three [hfac] anions to the Mg²⁺ ion through the two oxygen atoms of each [hfac] anion.