Before revision: 5-coordinate compounds To distinguish whether the geometry of the coordination center is trigonal bipyramidal or square pyramidal, the (originally just ) parameter was proposed by Addison et al.
After revision: File:Tau5 parameter for selected geometries.gif5-coordinate compounds To distinguish whether the geometry of the coordination center is trigonal bipyramidal or square pyramidal, the (originally just ) parameter was proposed by Addison et al.