Nonclassical carbenes as noninnocent ligands

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

“…The privileged pincer ligand platform has indulged a plethora of elements, reactivities, and applications. − It has been widely celebrated for the stabilization it imparts to the chelated entity, and more recently, ligand noninnocence accessible through tailored ligand design. − This includes redox noninnocence − and ligand-metal-mediated processes, − which have witnessed an exponential surge in interest due to the reactivity accessible through this multipronged approach to bond activation. Control over 5- or 6-membered chelation at position E (as exemplified for the carbazole-based pincer ligand shown in Figure ) extends the range of reactivity available with a pincer ligand in hand, while introduction of chirality at R could lead to stereoselective processes. − Immobilization strategies are another possibility, usually by modifying the backbone of the ligand at position Z (see Figure per illustration), leading to an immobilized catalyst retaining its selectivity and reactivity while being recycled several times. − These attributes, among others, have rendered pincer ligands an attractive platform from which to prepare tailored complexes.…”