Homoleptic Noble Gas Complexes of Rhombic Be 2 X 2 Clusters: Stability and Nature of the Ng⋯Be Interaction

ABSTRACT Rhombic Be 2 X 2 clusters (X = O, S, Se, and Te) provide electron‐deficient Be centers capable of coordinating noble gas (Ng) atoms. Here, the structures, energetic stability, and bonding of Be 2 X 2 and their homoleptic Ng 2 Be 2 X 2 complexes (Ng = He, Ne, Ar, Kr, Xe, and Rn) were investigated using correlated wavefunction calculations and complementary bonding analyses. Structural searches identified D 2h ‐symmetric rhombic geometries as the global minima for all Be 2 X 2 and Ng 2 Be 2 X 2 systems. The bare clusters are strongly bound against dissociation, although their stability decreases from Be 2 O 2 to Be 2 Te 2 . Ng bonding strength increases from Ar to Rn but generally weakens as X changes from O to Te, while the sequential dissociation energies reveal modest negative cooperativity between the two Ng⋯Be interactions. The He and Ne complexes exhibit very small dissociation energies. Natural population analysis indicates a gradual increase of Ng‐to‐Be electron donation toward the heavier noble gases. QTAIM descriptors indicate the presence of some degree of covalent character in the Ng⋯Be contacts. EDA‐NOCV analysis confirms that stabilization results from a combination of orbital, electrostatic, and dispersion effects. In the Ng–Be interactions of Ng 2 Be 2 X 2 , orbital interactions dominate over electrostatics and arise mainly from two Ng(ρ σ ) → Be 2 X 2 donation channels (in‐phase and out‐of‐phase). Overall, these complexes are best described as polarized donor–acceptor assemblies, whose bonding character depends jointly on the Ng and the Be 2 X 2 core.