In a vacuum-sealed flask on a lab bench in Germany sits an emerald-green crystal that will cause some jaws to drop. The crystal is the first stable compound containing a triple chemical bond between two boron atoms, a feat that had previously been limited to only two other non-metal elements – carbon and nitrogen.

Boron occupies a special spot in the periodic table. Each atom has three outer electrons, the minimum number needed to form a triple bond. But the element is flanked on all sides of the table by atoms that take very different bonding strategies. A world of previously forbidden chemistry beckons. “They did not simply find a new flower or a new plant,” says Gernot Frenking of the Philipp University of Marburg in Germany. “They opened the door to a new garden.”