OLi₄Au₄^2-: A Planar Tetracoordinate Oxygen Cluster with an OLi₄ Core Armored by Gold

Planar tetracoordinate oxygen (ptO) represents a significant challenge in hypercoordinate chemistry due to oxygen's high electronegativity and strong preference for localized bonding. While recent studies have revealed stabilization mechanisms dominated by electrostatic interactions, the design of ptO clusters with inert, functional peripheral frameworks, particularly those incorporating noble metals, remains unexplored. Herein, we theoretically design a star-like dianion cluster, OLi₄Au₄^2-, which features a central ptO atom electrostatically confined within a Li₄ square, itself armored by a rigid ring of gold atoms. Combined density functional theory and coupled-cluster calculations identify this D_4h-symmetric structure as a global minimum. Bonding analysis confirms the dominance of electrostatic interactions, with negligible covalent character between O and Li. Born-Oppenheimer molecular dynamics simulations attest to its excellent dynamic stability. This work introduces the first ptO cluster stabilized by a noble metal framework, offering a novel design paradigm for planar hypercoordinate systems with customizable peripheries and potential applications.