Geometrical Isomerism in Complexes
Stereoisomerism arising from different spatial arrangements of ligands around the metal centre.
Formula / equation
cis / trans, fac / mer
Unit
Dimensionless
In depth
Square planar MA₂B₂ complexes and octahedral MA₄B₂ complexes both give cis and trans forms, while octahedral MA₃B₃ complexes give facial and meridional forms. Tetrahedral complexes cannot show this isomerism because all four positions are adjacent.
Examples in the real world
Cisplatin being an effective anticancer drug while the trans isomer is inactive.