Ionic liquids in colloidal regime

Although the true nature of the catalyst is not always clear when mononuclear complexes are used as pre-catalysts in hydrogenation reactions, with cluster compounds employed as the pre-catalyst, it is frequently found that the active species is colloidal and review articles are available on how to distinguish between homogeneous and heterogeneous regimes.[43,441 A summary of hydrogenation reactions with metal-clusters in ionic liquids is provided in Table 3.4. 

---