Multifunctional ligands in transition metal catalysis

• Published in: New journal of chemistry 2011-01, Vol.35 (1), p.18-23
• Main Author: Crabtree, Robert H
• Format: Article
• Language: English
• Subjects: catalysis (homogeneous), catalysis (heterogeneous), bio-inspired, hydrogen and fuel cells, materials and chemistry by design, synthesis (novel materials); INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c0nj00776e

Sophisticated ligands are now being designed that do far more than just fulfil their traditional spectator roles by binding to the metal and providing a sterically-defined binding pocket for the substrate in homogeneous transition metal catalysis. This Focus review emphasizes selected cases in which ligands carry additional functional groups that change the properties of the ligand as a result of an external stimulus or undergo catalytically-relevant ligand-based reactivity. These include proton responsive ligands capable of gaining or losing one or more protons, ligands having a hydrogen bonding function, electroresponsive ligands capable of gaining or losing one or more electrons, and photoresponsive ligands capable of undergoing a useful change of properties upon irradiation. Molecular recognition ligands and proton coupled electron transfer (PCET) are briefly discussed. Ligands can do far more than bind to a metal. They can also carry additional functional groups that can respond to an external stimulus: e.g. , proton responsive, hydrogen bonding, electroresponsive and photoresponsive ligands.