Planar tetracoordinate fluorine in a FMg₄Se₄^- cluster

Planar hypercoordination has fascinated chemists for decades because of its exotic bonding properties. However, the preference for delocalized multicenter bonding makes it difficult for highly electronegative elements to achieve the planar hypercoordinate configuration. For fluorine, the most electronegative element, clusters with planar tetracoordination have been predicted recently, but its family members are scarce. Herein, a star-like D_4h-symmetry cluster FMg₄Se₄^- featuring a planar tetracoordinate fluorine (ptF) is predicted theoretically. The planar configuration of FMg₄Se₄^- results from electrostatic interactions between the central ptF and the Mg₄Se₄ framework, while the covalent interactions ensure the Mg₄Se₄ star-like skeleton. In addition, it possesses an excellent electronic structure as reflected by the wider HOMO-LUMO gap of 5.85 eV and positive vertical detachment energy of 5.24 eV. With its dynamic stability, cluster FMg₄Se₄^- is a promising target for further experimental synthesis and characterization.