Syntheses and catalytic applications of the transition metal complex-functionalized ionic liquids

The ligand- and transition metal complex-functionalized ionic liquids (FILs) can be defined narrowly as the ionic ligands and ionic transition metal complexes since they are not strictly room temperature ionic liquids (RTILs) any more in the range of RT to 100°C. Such kinds of ligand- and transition metal complex-FILs have attracted more and more attention due to their promising applications in homogeneous catalysis as one of alternative methods to heterogenize the homogenous catalysts into the RTILs phase. Due to similarity in the composition and the ionic structure to the parent RTILs (as a solvent), the ligand- and transition metal complex-FILs as catalysts have the following advantages. The catalysts are stable, and their leaching can be avoided, which make the separation workup simple. In addition, the recyclability of the catalysts is available. This review summarizes the progress in the syntheses of ligand- and transition metal complex-FILs and their applications in homogeneous catalysis, developed in the past decade.