H©Li₄Au₄⁻: Planar Tetracoordinate Hydrogen in an Electrostatic Interaction Dominated Superhalogen Anion

Planar hypercoordination has intrigued researchers for decades, yet hydrogen remained absent from this category until recently. Despite some advancements, further exploration of the emerging field of planar hypercoordinate hydrogen chemistry is still necessary. Herein, we report a D_4h symmetric H©Li₄Au₄ ^- cluster containing a planar tetracoordinate hydrogen (ptH) center. Both density functional theory (DFT) and ab initio calculations revealed that designed H©Li₄Au₄ ^- is a real global minimum. Meanwhile, it also possesses excellent dynamic stability. This stability is dominated by electrostatic interactions, and reinforced by multicenter covalent bonds rather than any aromaticity. Interestingly, it is the first superhalogen anion in the ptH cluster and is expected to experimental synthesis and characterization.