May 5, 2024

Revolutionizing Organometallic Chemistry: The 21-Electron Metallocene “Sandwich”

” Having more than 18 electrons is known to be uncommon because if you deviate from 18, the chemical bonds of the metallocenes start to extend, break, and change structure. We included 2 more electrons to a 19-electron metallocene and produced a 21-electron metallocene. I think most individuals didnt think this was possible, but our 21-electron metallocene is steady in service and solid states and can be stored for a long time,” Dr. Takebayashi discussed.
Because the sandwich structure of metallocenes can quickly be changed, the most challenging part of the research study was for the scientists to show that the nitrogen had effectively bonded to the cobalt without changing the sandwich structure. They had to carefully show that the metallocene was appropriately bonded to all nearby carbon atoms and that the nitrogen atom was connected to the cobalt atom.

Crystal structure of the freshly synthesized 21-electron metallocene compound showing the nitrogen (blue), cobalt (red), hydrogen (green), and carbon (grey) atoms. Credit: Takebayashi et al., 2023
The finding has potential to open new directions in energy, catalysis, and medicine.
Organometallic compounds, molecules made up of metal atoms and natural molecules, are often utilized to speed up chemical responses and have actually played a significant role beforehand the field of chemistry.
Metallocenes
Metallocenes, a kind of organometallic compound, are understood for their versatility and unique “sandwich” structure. Their discovery was a significant contribution to the field of organometallic chemistry and led to the awarding of the Nobel Prize in Chemistry in 1973 to the scientists who found and discussed their sandwich structure.

The adaptability of metallocenes is due to their ability to “sandwich” several components to form a variety of substances. They can be utilized in various applications, including the production of polymers, glucometers– used to determine the quantity of glucose in the blood, perovskite solar batteries, and as a catalyst, a substance that increases the rate of a chain reaction without being consumed or altered by the response itself.
Examples of metallocene chemical substances, their electron counts, and applications. Credit: Takebayashi et al., 2023
Recent Development at OIST
Dr. Satoshi Takebayashi, a researcher at the Science and Technology Group at the Okinawa Institute of Science and Technology (OIST), together with Dr. Hyung-Been Kang, a scientist at OISTs Engineering Section, and researchers from Germany, Russia, and Japan, has effectively developed a brand-new metallocene substance at OIST.
The chemical structure of metallocenes can accommodate a range of electron counts, enabling the development of complexes with as much as 20 electrons. However, the 18-electron structure is most favored as it is the most stable version.
” Having more than 18 electrons is known to be uncommon since if you differ 18, the chemical bonds of the metallocenes start to elongate, break, and change structure. However, we added 2 more electrons to a 19-electron metallocene and developed a 21-electron metallocene. I believe a lot of individuals didnt believe this was possible, but our 21-electron metallocene is stable in option and solid states and can be stored for a very long time,” Dr. Takebayashi explained.
With this brand-new metallocene, we can possibly create unique materials that can be used for applications in medicine, catalysis, and the energy sector, assisting to resolve important worldwide issues and improving our quality of life.
Obstacles and Collaboration in Research
Because the sandwich structure of metallocenes can easily be modified, the most difficult part of the research study was for the scientists to show that the nitrogen had effectively bonded to the cobalt without altering the sandwich structure. They had to rigorously show that the metallocene was appropriately bonded to all nearby carbon atoms and that the nitrogen atom was connected to the cobalt atom. To do this, Dr. Takebayashi arranged a strong team of researchers with various specialties and unambiguously showed that all the aspects had actually bonded well.
” This advancement would not have actually been possible without the participation of my collaborators who did substantial work,” Dr. Takebayashi included. Dr. Satoshi Takebayashi, Jama Ariai, Dr. Urs Gellrich, Sergey Kartashov, Dr. Robert Fayzullin, Dr. Hyung-Been Kang, Dr. Takeshi Yamane, Dr. Kenji Sugisaki, and Prof. Kazunobu Sato have actually coauthored an article released in the journal Nature Communications detailing their discovery.
Looking Ahead
Dr. Takebayashis future research study will focus on the usage of the 21-electron metallocene for more suitable science such as catalysis and material science, along with the discovery of extraordinary organometallic chemistry based upon this finding.
Reference: “Synthesis and characterization of an official 21-electron cobaltocene derivative” 5 September 2023, Nature Communications.DOI: 10.1038/ s41467-023-40557-7.