Inhibition of Catalytic Activity in Ionic Liquids: Implications for Catalyst Design and the Effect of Cosolvents

As a consequence of inherently weak interactions between the chloride anion and the 1-butyl-3-methylimidazolium cation (ca. 15 kJ/mol), chloride dissociation from a transition-metal complex can be thermodynamically disfavored in ionic liquids. Therefore, when chloride dissociation is a crucial step for the formation of the active catalytic species, the activity of the catalyst precursor might be completely inhibited in ionic liquids.