Heavy-metal cluster sets size record for metal aromaticity

12 bismuth ring creates ‘substantial’ π aromaticity with only two aromatic electrons

A 12-membered bismuth ring has become the biggest Hückel aromatic molecule made purely from metal atoms.1 Despite having only two π electrons, the compound’s ring current – an indicator of aromaticity – is similar to that of porphine with its 26 π-electrons.