A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be₂O₂–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)

Short interatomic distances below standard values for a single bond are usually identified with double or triple bonds. The synthesis and spectroscopic characterization of a molecule is reported where the distance between two beryllium atoms is shorter than a standard double bond but there is no bond. The cyclic diberyllium dioxide Be₂O₂molecule, which is coordinated by two noble gas atoms in Ng−Be₂O₂−Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe) was isolated and spectroscopically identified in low-temperature matrices. The complexes possess very short Be−Be distances, but the analysis of the electronic structure reveals that there is no chemical bond.