Unprecedented pentacoordinate oxygen cluster isn’t so new after all

Scientists in China have theorised a star-shaped beryllium-based dianion, [O©Be₅O₅]²⁻, which holds the first example of a stable planar pentacoordinate oxygen within a small multiply charged anion, meaning the central oxygen is bonded to five beryllium atoms in a flat plane. Computational analysis indicates that the unique structure is stable as the central oxygen satisfies the octet rule and oxygen to beryllium π-backbonding stabilises the electron-deficient beryllium atoms.