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.