Sc-Cr Metal complexes open benzene ring

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SUMMARY

The recent study led by Jiaxiang Chu at the University of Chinese Academy of Sciences demonstrates a novel method for breaking the aromatic benzene ring using a scandium complex. This complex, which features a pincer-like ligand, was combined with potassium graphite (KC8) and benzene at room temperature, resulting in an inverted sandwich complex that allows benzene to carry four additional electrons. This innovative approach builds on previous work by Simon Aldridge's team at the University of Oxford, which utilized aluminum complexes for similar reactions. The study highlights scandium's unique properties, making it a valuable element in breaking strong chemical bonds.

PREREQUISITES
  • Understanding of scandium complexes and their chemical properties
  • Knowledge of pincer ligands and their stabilization effects
  • Familiarity with potassium graphite (KC8) as a reducing agent
  • Basic principles of aromaticity and electron delocalization in benzene
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  • Research the mechanisms of scandium complex reactions with aromatic compounds
  • Explore the applications of pincer ligands in organometallic chemistry
  • Investigate the potential of Sc-Cr complexes in degrading polyaromatic hydrocarbons
  • Learn about the synthesis and properties of aluminum complexes in aromatic transformations
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Chemists specializing in inorganic and organometallic chemistry, researchers focused on aromatic compound transformations, and professionals interested in the applications of scandium in chemical processes.

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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!
 
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.