D4h OMg4S42–: a global minimum featuring a planar tetracoordinate oxygen

Planar hypercoordinate oxygen clusters have remained challenging due to oxygen's high electronegativity and versatile bonding capabilities. Herein, OMg4S42-, a dynamically stable global minimum with a planar tetracoordinate oxygen, is designed theoretically. Its planar configuration is dominated by electrostatic interactions rather than covalent interactions.