Chemistry - Transition metals and complex ion formation
Transition metals and complex ion formation
Transition metal cations form complex ions and coordination complexes
(compounds containing complex ions) because their small radius and high
charge attract and hold onto species known as ligands.
All ligands have one or more non-bonding electron pairs, e.g. on the N
atom in the NH3 molecules. This electron pair is donated to or shared with
the transition metal cation, e.g. Cu. The bonding between the central
cation and the ligands is neither covalent nor ionic but intermediate
between these two types and generally classified as bonding.
The formation of specific complex ions can be very useful, especially in
dissolving normally insoluble compounds. Equilibrium principles are
A great deal of modern chemical research focuses on the structure,
properties and uses of coordination complexes, partly because they are
involved in many biological reactions. Haemoglobin and vitamin B12, for
example, are both coordination complexes - of iron and cobalt respectively.
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