Chalcogenones and Pincer Ligands: Coordination Chemistry and Interaction with Transition and Heavy Main Group Elements

This chapter highlights recent insights of pincer chemistry, regarding pincer chalcogenones and their metal complexes. Due to the diversity of the proligands and the quite large number of pincer–metal complexes, only compounds with heavier chalcogens (S, Se) in the pincer ligand are considered. Classical, symmetric proligands which can afford anionic pincer ligands or can behave as neutral pincer ligands resulting in metal complexes with fused 5- or 6-membered metallacycles are discussed, emphasizing general and specific methods of synthesis as well as their structural characteristics and reactivity. The ligands considered in this chapter are those based on a phenylene/heterophenylene (substituted pyridine or phosphinine) unit or a 5-membered cyclic fragment (e.g., indenyl, pyrrole, and related rings) as the central core, substituted with two side arms containing EZ groups. A particular designation of such ligands is used to show not only the donor atoms, but also the atoms to which the donors are bound and the size of the fused metallacycles formed by complexation, e.g., [(EZ)/X/(ZE]-5,5 (E = S, Se; Z = C, P; X = C, N). Applications of selected metal complexes in catalysis, biology, and materials science are briefly mentioned.