Rhenium complexes of porphyrinoids

Abstract

Rhenium coordination complexes offer a wide range of applications in various fields and have been emerged as a profound research area in recent years. Rhenium, being a group 7 congeners, shows rich coordination chemistry with different porphyrinoid ligands and formed complexes with rhenium metal stabilized in various oxidation states such as +I, +II,+III, +V and, +VII. In this article, we provide a comprehensive overview of the state-of-the-art rhenium porphyrinoids by detailing their synthesis, characterization, and reactivity studies. The historical overview of rhenium complexes of porphyrin, porphycene, N-confused porphyrin, N-fused porphyrin, core-modified porphyrins, corrole, triphyrin, and expanded porphyrin systems are described, and in each case, the distinct role of the porphyrinoid ligand in stabilizing the corresponding rhenium complex as well as their reactivity are discussed. The high and low-valent rhenium porphyrinoid complexes helped to understand the rhenium-heteroatom (Re–X) bonding features, fluxional behaviour, Re-Re multiple bond formation, and their luminescent properties. Due to their extraordinary features, the rhenium porphyrinoids have great potential applications in various fields, including modern-day materials and catalysis research. We hope that this article will be helpful to further design and develop new rhenium porphyrinoids in the future.