Simulating the effect of a triple bond to achieve the shortest main group metal–metal distance in diberyllium complexes: a computational study

Abstract

The subject of metal–metal bonding interactions in molecular systems continues to attract research interest. Chromium heretofore has been the only element known to afford metal–metal distances shorter than 1.700 Å in the form of Cr–Cr multiple bonds. In this computational study, the effect of a triple bond on reducing interatomic distances is simulated through forming three non-classical bonding orbitals between two beryllium atoms, thereby realizing the remarkably short Be–Be distances (1.692–1.735 Å) in kinetically stable global minimum species [L → Be₂H₃ ← L]⁺ (L = NH₃, PH₃, and noble gases Ne–Xe). Such diberyllium complexes make promising candidates for experimental realization. In particular, the Be–Be distance of 1.692 Å in [Ne → Be₂H₃ ← Ne]⁺ represents the first example of global minimum having a main group metal–metal distance under 1.700 Å. [TEA → Be₂H₃ ← TEA]⁺, which contains the bulky triethylamine (TEA) ligands, is designed as a more promising target for synthesis and isolation in condensed states.