Planar tetracoordinate fluorine stabilized by rigid Zn₄Po₄, Cd₄Te₄, and Cd₄Po₄ rings

Stabilizing planar tetracoordinate fluorine (ptF) remains challenging, as its high electronegativity restricts electron delocalization. "Altering the rigidity of the ligand ring" is an effective way to expand the ptF family. Herein, we use rigid ligand rings to stabilize the ptF center, which are made of zinc-group ligands and oxygen-group auxiliary atoms. Among fifteen star-like F©M₄X₄^- (M = Zn-Hg; X = O-Po) systems, only F©Zn₄Po₄^-, F©Cd₄Te₄^- and F©Cd₄Po₄^- clusters with D_4h symmetry are true global minima (GMs) on the potential energy surfaces. Bonding analyses indicate that the stabilities of the ptF centers in these systems are attributed to multicenter ionic bonding. Interestingly, the ptF F©Zn₄Po₄^-, F©Cd₄Te₄^- and F©Cd₄Po₄^- clusters are exotic superhalogen anions with robust electronic structures, based on high vertical detachment energies (4.18, 4.39, and 4.12 eV). The present work not only diversifies the ptF types but also provides a new strategy to design planar hypercoordinate fluorine species.