# Isostructural

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{{Short description|Compounds having similar chemical structure}}
'''Isostructural''' [chemical compound](/source/chemical_compound)s have similar [chemical structure](/source/chemical_structure)s. "[Isomorphous](/source/Isomorphism_(crystallography))" when used in the relation to [crystal structure](/source/crystal_structure)s is not synonymous: in addition to the same atomic connectivity that characterises isostructural compounds, isomorphous substances crystallise in the same [space group](/source/space_group) and have the same [unit cell](/source/unit_cell) dimensions.<ref>{{cite book |last=Wells |first=A. F. |title=Structural Inorganic Chemistry |edition=3rd |year=1970 |publisher=Clarendon Press |location=Oxford |isbn=0-19-855125-8 |page=182}}</ref> The [IUCR](/source/International_Union_of_Crystallography) definition<ref>[http://reference.iucr.org/dictionary/Isostructural_crystals "Isostructural crystals"], IUCR Online Dictionary of CRYSTALLOGRAPHY.</ref> used by crystallographers is:
{{blockquote|Two crystals are said to be isostructural, if they have the same structure, but not necessarily the same cell dimensions nor the same chemical composition, and with a "comparable" variability in the atomic coordinates to that of the cell dimensions and chemical composition. For instance, calcite CaCO<sub>3</sub>, sodium nitrate NaNO<sub>3</sub> and iron borate FeBO<sub>3</sub> are isostructural. One also speaks of isostructural series, or of isostructural polymorphs or isostructural phase transitions. The term isotypic is synonymous with isostructural.}}

Examples include:
* I-[Gold(I) bromide](/source/Gold(I)_bromide) is isostructural with [gold(I) chloride](/source/gold(I)_chloride)
* [Borazine](/source/Borazine) is isostructural with [benzene](/source/benzene)
* [Indium(I) bromide](/source/Indium(I)_bromide) is isostructural with β-[thallium(I) iodide](/source/thallium(I)_iodide) and has a distorted rock salt structure.

Many minerals are isostructural when they differ only in the nature of a cation.

Compounds which are [isoelectronic](/source/isoelectronic) usually have similar chemical structures. For example, [methane](/source/methane), CH<sub>4</sub>, and the [ammonium](/source/ammonium) ion, NH<sub>4</sub><sup>+</sup>, are isoelectric and are isostructural 
as both have a [tetrahedral](/source/tetrahedral) structure. The C–H and N–H bond lengths are different and crystal structures are completely different because the ammonium ion only occurs in [salt](/source/salt_(chemistry))s.

== References ==
{{reflist}}

Category:Crystallography
Category:Molecular geometry

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Adapted from the Wikipedia article [Isostructural](https://en.wikipedia.org/wiki/Isostructural) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Isostructural?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.