Sc-Cr Metal complexes open benzene ring

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Benzene's aromaticity presents significant challenges for conversion into linear products under mild conditions. Recent research led by Jiaxiang Chu highlights a novel method using a scandium complex with a pincer-like ligand to interact with benzene. This approach builds on previous work, such as a 2019 aluminum complex that facilitated benzene ring opening. The new study involves mixing the scandium complex with potassium graphite and benzene at room temperature, resulting in an inverted sandwich complex where benzene binds to the scandium complex, allowing it to carry extra electrons in its antibonding orbitals. Scandium's unique properties, including its small size and high charge, enable reactions that other metals cannot achieve, making it a valuable element in this context. The discussion also raises questions about the potential for scandium-chromium complexes to degrade polyaromatic compounds, suggesting further exploration in this area.
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https://cen.acs.org/physical-chemis...3/web/2025/07?sc=250723_sc_eng_fb_cen_boosted

Benzene’s aromaticity makes it a tough nut to crack, and there are very few ways to convert it into linear products under mild conditions, says Jiaxiang Chu of the University of Chinese Academy of Sciences, who led the experimental aspects of the work.

Back in 2019, for example, a team led by Simon Aldridge at the University of Oxford made an aluminum complex that inserts itself into benzene, priming it for a reaction with a tin reagent that breaks open the ring. In addition, certain enzymes can pry open the benzene ring in catechol.

The team behind the new study instead drew inspiration from the kinds of metal complexes that can break the strong bonds in dinitrogen or carbon monoxide. First they made a scandium complex containing a pincer-like ligand that stabilizes a range of metal oxidation states. Then they mixed the complex with potassium graphite (KC8), which is a strong reducing agent, and benzene at room temperature. This formed an inverted sandwich complex in which each of benzene’s faces binds to a scandium complex. In this arrangement, the benzene carries four extra electrons in its antibonding orbitals.

“Scandium is always good for a surprise because it’s one of the smallest, highest-charged metal cations,” says Sjoerd Harder of Friedrich Alexander University Erlangen-Nuremberg, an organometallic chemist who uses main-group metal complexes to activate strong bonds. Harder was not involved in the new work. “It can do stuff that other metals can’t do.”
 
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It is always interesting to see Scandium getting applied.

We inorganic chemists sometimes forget that the first row doesn't start at titanium!
 
Sc and Y are interesting elements.

Sc is a useful strengthener in Al. Sc is also very expensive given that is produced in few mines.

https://en.wikipedia.org/wiki/Scandium#Applications

https://pubsapp.acs.org/cen/80th/print/scandium.html
https://periodic-table.rsc.org/element/21/scandium

https://www.aemree.com/news/interesting-facts-about-scandium.html


I wonder if it Sc-Cr oomplexes could degrade/decompose polyaromatic compounds, e.g., PCBs, biphenyls, triphenyls, etc.
 
I havent perused the article, but their illustrations suggest that the benzene ring coordinates axially to the Sc/Sc active site. I am not sure how well polyaromatics can emulate this.
 

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