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Shapes of Complex Ions

Chemistry: Cambridge International A Level, topic 2.4.3

Shape of Complex Ions

Complex ions display many different shapes depending on the metal and the ligands involved.

Geometries

Geometries

  • There are four main geometries for complex ions.
  • Octahedral: commonly seen with small ligands like water and ammonia.
  • Tetrahedral: commonly seen with large ligands like chloride.
  • Square planar: commonly seen with the metals Ni, Pd, Pt.
  • Linear: very rare and only seen for Cu, Ag, Au.
Square planar complexes

Square planar complexes

  • Square planar complexes are usually only seen for the metals Ni, Pd, Pt.
  • The reasons for this are complex.
  • Square planar complexes can also have cis-trans (Z/E) isomerism.
  • This is illustrated for the complex [Pt(NH3)2Cl2] above.
Linear complexes

Linear complexes

  • Linear complexes are only seen for Cu, Ag, and Au.
  • A good example of a linear complex is [Ag(NH3)2]+.
  • This is the ingredient in Tollen's reagent.

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