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.
The new metal hydride displays σ aromaticity © ACS
Anastassia Alexandrova (Photo: Reed Hutchinson/UCLA Newsroom)