Editing Coordination complex (section)

====Stereoisomerism====
[[Stereoisomerism]] occurs with the same bonds in distinct orientations. Stereoisomerism can be further classified into:<ref>von Zelewsky, A. "Stereochemistry of Coordination Compounds" John Wiley: Chichester, 1995. {{ISBN|0-471-95599-X}}.</ref>

=====Cis–trans isomerism and facial–meridional isomerism=====
[[Cis–trans isomerism]] occurs in octahedral and [[square planar]] complexes (but not tetrahedral). When two ligands are adjacent they are said to be '''cis''', when
opposite each other, '''trans'''. When three identical ligands occupy one face of an octahedron, the isomer is said to be facial, or '''fac'''. In a ''fac'' isomer, any two  identical ligands are adjacent or ''cis'' to each other. If these three ligands and the metal ion are in one plane, the isomer is said to be meridional, or '''mer'''. A ''mer'' isomer can be considered as a combination of a ''trans'' and a ''cis'', since it contains both trans and cis pairs of identical ligands.

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Image:Cis-dichlorotetraamminecobalt(III).png|{{chem2|''cis''\-[CoCl2(NH3)4]+}}
Image:Trans-dichlorotetraamminecobalt(III).png|{{chem2|''trans''\-[CoCl2(NH3)4]+}}
Image:Fac-trichlorotriamminecobalt(III).png|{{chem2|''fac''\-[CoCl3(NH3)3]}}
Image:Mer-trichlorotriamminecobalt(III).png|{{chem2|''mer''\-[CoCl3(NH3)3]}}
</gallery>
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=====Optical isomerism=====
[[Optical isomerism]] occurs when a complex is not superimposable with its mirror image.  It is so called because the two isomers are each [[optically active]], that is, they rotate the plane of [[polarized light]] in opposite directions. In the first molecule shown, the symbol Λ (''[[lambda]]'') is used as a prefix to describe the left-handed propeller twist formed by three bidentate ligands.  The second molecule is the mirror image of the first, with the symbol Δ (''[[delta (letter)|delta]]'') as a prefix for the right-handed propeller twist. The third and fourth molecules are a similar pair of Λ and Δ isomers, in this case with two bidentate ligands and two identical monodentate ligands.<ref>{{Cite book|isbn=978-0-13-841891-5 |last=Miessler|first=Gary L.|author2=Donald Arthur Tarr|title=Inorganic Chemistry|year=1999|pages=315, 316|chapter=9|publisher=Prentice Hall }}</ref>

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Image:Delta-tris(oxalato)ferrate(III)-3D-balls.png|[[Potassium ferrioxalate|{{chem2|Λ\-[Fe(ox)3](3-)}}]]
Image:Lambda-tris(oxalato)ferrate(III)-3D-balls.png|{{chem2|Δ\-[Fe(ox)3](3-)}}
Image:Delta-cis-dichlorobis(ethylenediamine)cobalt(III).png|[[cis-Dichlorobis(ethylenediamine)cobalt(III) chloride|{{chem2|Λ\-''cis''\-[CoCl2(en)2]+}}]]
Image:Lambda-cis-dichlorobis(ethylenediamine)cobalt(III).png|{{chem2|Δ\-''cis''\-[CoCl2(en)2]+}}
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