Chemical bonding in xenon fluorides

Structures of xenon compounds (small shaded circles represent the O atoms)  

A similar treatment, involving two 3c-4e bonds located in X and Y directions, accounts satisfactorily for the planar structure of XeF4. The remaining 5s and 5pz AOs of Xe are hybridized to form sp hybrid orbitals that accommodate the two lone-pair electrons, as shown in Fig. 17.5.2(e). The crystal structure of XeF2 is analogous to that of a-KrF2, which is illustrated in Fig. 17.5.8(a) (see below). 

Molecular orbitals of the 3c-4c F-Xe-F a bond of XeF2 (a) the possible combinations of the AOs of Xe and F atoms, and (b) the schematic energy levels of XeF2 molecule. 

There are two possible theoretical models for the isolated XeFg molecule  

There are nine electron pairs in XeFg-, which are to be accommodated around the Xe atom. From experimental data, the XeFg ion has a square antiprismatic structure [Fig. 17.5.2(o)] showing no distortion that could reveal a possible position for the nonbonding pair of electrons. The lone pair presumably resides in the spherical 5s orbital. 

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