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Updated: Sep 16, 2025
Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology
Published on: March 12, 2015
From 18- to 20-electron ferrocene derivatives via ligand coordination
Satoshi Takebayashi1, Jama Ariai2, Sergey V Kartashov3
1Organometallic Chemistry Group, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan. satoshi.takebayashi@oist.jp.
None:
The 18-electron rule is a fundamental rule in coordination chemistry on which several revolutionary discoveries in catalysis and materials science are founded. This rule has classes of exceptions; however, it is widely taught and accepted that diamagnetic 18-electron complexes do not coordinate to a ligand to form a 20-electron complex even as a reaction intermediate. Here, based on tunable ligand design, we report the formation of 20-electron ferrocene derivatives through reversible nitrogen coordination to 18-electron analogs. Through theoretical studies, we have elucidated key features that enabled this coordination chemistry and how the nitrogen coordination shifts the metal-ligand bonding characters. These 20-electron ferrocene derivatives exhibit reversible FeII/FeIII/FeIV redox chemistry under previously unattainable, mild conditions. This work highlights the previously unknown coordination chemistry of diamagnetic 18-electron complexes, which underlies the foundation for future innovations in a range of synthetic chemistry.
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