Beryllium doubles down on nitrogen bonding

Metals on the west wing of the periodic table—the s-block elements—almost never form double bonds, because of the meager capacity of their s orbitals. Now, a team led by Robert J. Gilliard Jr. of the University of Virginia and David Wilson of La Trobe University has created the first known compound to contain a multiple bond between an s-block metal and nitrogen (Angew. Chem., Int. Ed. 2021, DOI: 10.1002/anie.202016027). As well as being the first beryllium imido complex, the compound boasts the shortest beryllium-nitrogen bond on record. The team synthesized the complex using a precursor containing a carbon-beryllium-carbon group, which reacted with trimethylsilyl azide to form the new beryllium imido complex in 43% yield. The researchers’ X-ray crystallography data and quantum calculations indicate that the complex contains a beryllium-nitrogen double bond, originating from σ and π donation from the nitrogen atom. “More and more, we are discovering that main-group elements can participate in bonding scenarios that were previously reserved for transition metals,” Gilliard says. Transition-metal imido complexes are widely used in catalysis but often rely on expensive metals. Gilliard hopes that the oxidation chemistry used to make the beryllium complex may pave the way to alternative catalysts made from cheap and abundant alkaline earth metals such as magnesium.