A Very Short Be-Be Distance but No Bond: Synthesis and Bonding Analysis of Ng-Be2 O2 -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 Be2 O2 molecule, which is coordinated by two noble gas atoms in Ng-Be2 O2 -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.