LigandEnabled

Ligandenabled is a term used in coordination chemistry and catalysis to describe systems in which the ligand framework actively contributes to enabling or enhancing a chemical transformation that the metal center alone would not achieve. The concept emphasizes how ligand design can modulate electronic structure, geometry, and reaction pathways, sometimes allowing multi-electron processes, selective activation, or unusual oxidation states.

Mechanistically, ligands can influence reactivity through several routes. They can donate or withdraw electron density to tune the metal’s properties, participate in electron transfer as redox-active or non-innocent partners, provide secondary coordination sites for substrates, or stabilize high-energy intermediates. Hemilabile or cooperative ligands enable metal–ligand cooperation, where both components undergo reversible changes during a catalytic cycle. The approach often involves designing ligands that participate in proton or hydride transfers, or that facilitate substrate binding and release in concert with the metal.

Applications of the ligand-enabled approach span various catalytic fields, including cross-coupling, hydrogenation, and C–H activation, as well as electrochemical and photocatalytic transformations. Redox-active ligands, pincer and macrocyclic architectures, and other cooperative designs have expanded capabilities for small-molecule activation and multi-electron processes.

Terminology varies in the literature; ligandenabled describes a design philosophy rather than a single mechanism. It highlights the active role of ligands in extending reactivity, selectivity, and efficiency beyond what metal centers can achieve alone.