Dibromine Promoted Transmetalation of an Organomercurial by Fe(CO)5: Synthesis, Properties, and Cytotoxicity of Bis(2-C6H4-2′-py-κC,N)dicarbonyliron(II)

Electronic Structure and Geometry of the Lowest 2LMCT State of Fe(III) Potential Fluorescent Emitters†

Metal complexes with a 3d⁶ electron count are emerging as an alternative to 4d⁶-based photosensitizers, emitters, or photoredox catalysts. In recent years, several Fe(II) potential emitters have been proposed, based on strongly donating ligand sets. Those tend to facilitate oxidation to their 3d⁵ species, whose photophysics is based on low-lying ligand-to-metal charge-transfer (LMCT) states. The geometry and electronic structure of ²LMCT states are unveiled in this work.

The Exchange of Cyclometalated Ligands

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C-H bond activation by transition metal complexes and C-M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.