Square Planar Complex
A four-coordinate complex in which the ligands occupy the corners of a square around the metal.
Formula / equation
dsp² hybridisation
Unit
Dimensionless
In depth
Square planar geometry results from an extreme tetragonal distortion that leaves the d_x²−y² orbital very high in energy, so it is strongly favoured by d⁸ metals with strong field ligands. It permits cis and trans isomerism, unlike the tetrahedral alternative.
Examples in the real world
[Ni(CN)₄]²⁻, [PtCl₄]²⁻, and cisplatin, whose anticancer activity depends on its cis geometry.