Polar, weakly coordinating ionic liquids as solvents for fundamental organometallic reactions

Room Temperature Ionic liquids (RTILs) are potentially highly polar, weakly-coordinating, room temperature liquids that are potentially good solvents for organometallic reactions where the active species of the metal center is a cationic complex. RTILs are not new, but their popularity has recently resurged as possible alternatives to common organic solvents. In contrast to organic solvents, RTILs have low volatility, are non-flammable, and have a high thermal stability. Also, due to the large number of possible anion/cation combinations it is possible to create tunable solvents for organic/inorganic reactions. The most important property is that RTILs can be polar and weakly-coordinating. In this study reactions were chosen where the active metal complex is cationic.; We hypothesized that RTILs have the potential to accelerate reactions, such as polymerizations and oxidative additions, by not only providing a polar environment for the cationic complex, but also by providing stabilization for charged species. In this study, basic types of reactions were explored. Olefin polymerizations (polymerization of ethylene, co-polymerization of CO/styrene, and ring opening metathesis polymerization) and oxidative addition (methyl iodide addition to iridium and rhodium centers) were optimized in the ionic liquids and the results compared to organic solvents.