In chemistry, the pentagonal planar molecular geometry describes the shape of compounds where five atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a pentagon.
The only two pentagonal planar species known are the isoelectronic (nine valence electrons) ions (pentafluoroxenate(IV)) and (pentafluoroiodate(III)). Both are derived from the pentagonal bipyramid with two lone pairs occupying the apical positions and the five fluorine atoms all equatorial.