Inversion element

Inversion i

An inversion can be thought of as a reflection through a point, such that an atom with coordinates of (x,y,z) will have coordinates of (-x,-y,-z) after the inversion. The resulting molecule will be indistinguishable from the original.

Neither water nor chloroform (examples from the rotation and mirror plane pages) has no inversion center. Instead we will use hydrogen peroxide (H₂O₂) as an example. In this case, the inversion center lies between the two oxygens.

Square planer PtCl₄^2- has an inversion center on the Pt atom. During an inversion, Cl^a and Cl^c would exchange positions, and Cl^b and Cl^d would exchange positions. This differs from a mirror plane in that a mirror plane would involve Cl^a and Cl^b exchanging positions, and Cl^c and Cl^d exchanging positions. The inversion is best seen using a ball and stick model.