STABILIZATION OF CATIONIC IRIDIUM HYDROGENATION CATALYSTS VIA INTERCALATION IN MONTMORILLONITE CLAY

The olefin hydrogenation catalysts [Ir(COD)(PPh3)2]+ and [Ir(COD)(NCMe)(PCy3)]+ have been intercalated in montmorillonite clay via an ion-exchange procedure. While the initial activity of the intercalated catalysts for the hydrogenation of cyclohexene is generally 50-80% of that of their homogeneous analogues, the intercalated catalysts remain active for longer periods, indicating that dimer- and trimer-forming reactions, responsible for deactivation of the homogeneous catalysts, are partially suppressed upon intercalation. In the hydrogenation of 1-hexene the activity of [Ir(COD)(NCMe)(PCy3)][BPh4] for the competing process of double bond isomerisation is found to increase with the catalyst concentration.