Abstract
Influencing electron distribution within a coordination complex bearing redox-active ligands offers the possibility to foster new reactivities. This redistribution can involve electrons but also protons or more elaborate chemical groups. Often perceived as a liability, chemical non-innocence can actually be considered a synthetic tool in which the synergy between metal and ligand leads to chemical reactivity at the ligand that is part of a streamlined process, rather than an unwanted side reaction. This concept article aims at providing examples of how redistributing electron density within a metal complex bearing redox-active ligands can foster interesting functionalization chemistry. This seemingly fundamental question has very practical applications in the fields of hydrogenation and energy-related catalytic reactions such as small-molecule activation, solar fuels, or to make new (photo)catalysts and noncanonical redox cofactors.
Graphical Abstract
While often perceived as a liability, ligand-based reactivity in carefully designed settings becomes a powerful synthetic tool. The key to streamlined processes overriding classical ionic reactivity is the selective electron redistribution induced by metal coordination. This enables storage of electrons and protons or incorporation of functional groups in mechanistic manifolds of relevance in small-molecule activation as well as synthetic analogs of redox-active cofactors.
