Editing Coordination complex (section)

==Application of coordination compounds==
As metals only exist in solution as coordination complexes, it follows then that this class of compounds is useful in a wide variety of ways.

===Bioinorganic chemistry===
In [[bioinorganic chemistry]] and [[bioorganometallic chemistry]], coordination complexes serve either structural or catalytic functions. An estimated 30% of proteins contain metal ions.  Examples include the intensely colored [[Vitamin B12|vitamin B<sub>12</sub>]], the [[Heme|heme group]] in [[hemoglobin]], the [[cytochrome]]s, the [[Chlorin|chlorin group]] in [[chlorophyll]], and [[carboxypeptidase]], a hydrolytic enzyme important in digestion. Another complex ion enzyme is [[catalase]], which decomposes the cell's waste [[hydrogen peroxide]]. Synthetic coordination compounds are also used to bind to proteins and especially nucleic acids (e.g. anticancer drug [[cisplatin]]).

===Industry===
[[Homogeneous catalysis]] is a major application of coordination compounds for the production of organic substances.  Processes include [[hydrogenation]], [[hydroformylation]], [[oxidation]].  In one example, a combination of titanium trichloride and triethylaluminium gives rise to [[Ziegler–Natta catalyst]]s, used for the [[polymerization]] of ethylene and propylene to give polymers of great commercial importance as fibers, films, and plastics.

Nickel, cobalt, and copper can be extracted using [[hydrometallurgy|hydrometallurgical processes]] involving complex ions. They are extracted from their ores as [[Metal ammine complex|ammine]] complexes. Metals can also be separated using the selective precipitation and solubility of complex ions. Cyanide is used chiefly for extraction of gold and silver from their ores.

[[Phthalocyanine]] complexes are an important class of pigments.

===Analysis===
At one time, coordination compounds were used to identify the presence of metals in a sample. [[Qualitative inorganic analysis]] has largely been superseded by instrumental methods of analysis such as [[atomic absorption spectroscopy]] (AAS), [[inductively coupled plasma atomic emission spectroscopy]] (ICP-AES) and [[inductively coupled plasma mass spectrometry]] (ICP-MS).