Elusive σ Aromaticity Captured

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Prof. Anastassia Alexandrova and colleagues have created a unique transition metal hydride in which the hydrogens form a five-membered aromatic ring – something that had been theorized but until now never seen. 

ChemistryWorld (by Simon Hadlington): Unlike ‘conventional’ π-aromaticity typified by benzene, here the delocalised electrons are shared across the pentagonal ring through planar σ bonds. This σ-aromaticity confers unusual stability on the hydride; if the phenomenon is more widespread than previously recognized – a real possibility say the researchers – this could have implications for the kinetics of transition metal catalysis in which hydrides form an intermediate species.  

You can read the rest of the article here. The Journal of Physical Chemistry Letters publication which this article is based on is available here.

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The new metal hydride displays σ aromaticity © ACS

Anastassia Alexandrova Photo 2
Anastassia Alexandrova (Photo: Reed Hutchinson/UCLA Newsroom)