Valence shell electron pair repulsion octahedral geometry

The molecular geometry of a complex depends on the coordination number, which is the number of ligand atoms bonded to the metal. The most common coordination number is 6, and almost all metal complexes with coordination number 6 adopt octahedral geometry. This preferred geometry can be traced to the valence shell electron pair repulsion (VSEPR) model Introduced In Chapter 9. The ligands space themselves around the metal as far apart as possible, to minimize electron-electron repulsion. 

But hadn t Gillespie predicted as early as 1962, using valence shell electron pair repulsion (VSEPR) arguments, that XeF should have a distorted octahedral geometry ... 

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