Complexes, like ions, have a definite shape. This shape results from both the number of things bound to the central metal ion (coordination number) and the electronic structure of the ion and the ligands.

Some common coordination numbers are 2, 4 and 6.

• Coordination 2 complexes are linear
• Coordination 4 complexes can be either tetrahedral or square planar
• Coordination 6 complexes are octahedral

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