Chemists snare 17-electron half-sandwich radical

After decades of trying, chemists have finally captured an elusive 17-electron chromium half-sandwich radical.

Carbonyl-containing 17-electron organometallic radical cations are important intermediates in many organic transformations but inherently unstable. Now, a team led by Xinping Wang from Nanjing University in China has successfully synthesised and characterised the organometallic radical cation [(C₆Me₆)Cr(CO)₃]⁺. Modelling revealed its bonding and showed that its unpaired electron is predominantly localised on the chromium atom.