biostudies-literatureUnknownCui LJFundamental Research Funds for the Central UniversitiesNational Natural Science Foundation of ChinaQuantum chemical calculations are reported for the complexes of alkaline earth metals AeOLi₂ (Ae = Be-Ba) at the BP86-D3(BJ)/def2-QZVPP and CCSD(T)/def2-QZVPPQZVPP levels. The nature of the Ae-OLi₂ bond has been analyzed with a variety of methods. The AeOLi₂ molecules exhibit an unprecedented σ donor bond Ae→OLi₂ where the (<i>n</i>)s² lone-pair electrons of the Ae atom are donated to vacant O-Li₂ antibonding orbitals having the largest coefficient at lithium. This is a covalent bond where the accumulation of the associated electronic charge is located at two positions above and below the Ae-OLi₂ axis. The bifurcated component of orbital interactions is structurally related to the recently proposed collective bondChemical sciencehttps://www.ebi.ac.uk/biostudies/studies/S-EPMC11337084biostudies-literatureUnusual quadruple bonds featuring collective interaction-type σ bonds between first octal-row atoms in the alkaline-earth compounds AeOLi₂ (Ae = Be-Ba).PMC1133708412374255Cui LJCui ZHPan SFrenking GLiu YQfalseUnusual quadruple bonds featuring collective interaction-type σ bonds between first octal-row atoms in the alkaline-earth compounds AeOLi₂ (Ae = Be-Ba).Quantum chemical calculations are reported for the complexes of alkaline earth metals AeOLi₂ (Ae = Be-Ba) at the BP86-D3(BJ)/def2-QZVPP and CCSD(T)/def2-QZVPPQZVPP levels. The nature of the Ae-OLi₂ bond has been analyzed with a variety of methods. The AeOLi₂ molecules exhibit an unprecedented σ donor bond Ae→OLi₂ where the (<i>n</i>)s² lone-pair electrons of the Ae atom are donated to vacant O-Li₂ antibonding orbitals having the largest coefficient at lithium. This is a covalent bond where the accumulation of the associated electronic charge is located at two positions above and below the Ae-OLi₂ axis. The bifurcated component of orbital interactions is structurally related to the recently proposed collective bond2024-01-01T00:00:00Z2024 Jul2025-04-21T22:17:55.458Z2025-04-05T18:41:53.179ZS-EPMC113370843917624510.1039/d4sc01979b