Forging small rings with large pnictogens

In a feat of synthetic inorganic chemistry, researchers have made the first methylenedistibiranes—three-membered rings that have two antimony atoms and a carbon atom. Researchers led by Alessandro Bismuto at the University of Bonn and Antonio Frontera at the University of the Balearic Islands crystallized and characterized the compounds ( J. Am. Chem. Soc. 2025, DOI: 10.1021/jacs.4c15626 ). Examples abound of rings that feature multiple nitrogen atoms—the lightest of the pnictogen elements. But making similar heterocycles from heavier pnictogen elements like antimony and bismuth is challenging because the orbital overlap trends and energies change dramatically as one moves down the pnictogen column in the periodic table. Bismuto says he and his colleagues were interested in making inorganic rings with multiple antimony atoms since they reasoned that such heterocycles would be reactive compared with linear Sb=Sb, which is not particularly reactive. First, the chemists used a [3 + 2] cycloaddition between distibene