Coordination chemistry is the study of coordinate covalent bonding by metal atoms, especially transition metal atoms.

This very exciting field is important to metallobiochemistry with respect to functions of enzymes which have transition metal atoms involved in their active sites. These atoms bind both small inorganic molecules and large organic ligands using coordinate covalent chemistry.

The number of ligands a metal binds is refered to as its coordination number. The cobalt atom in the vitamin B12 structure below has a coordination number of 6:

See jmol: Vitamin B12