Isostructural chemical compounds have similar chemical structures. "Isomorphous" when used in the relation to crystal structures is not synonymous: in addition to the same atomic connectivity that characterises isostructural compounds, isomorphous substances crystallise in the same space group and have the same unit cell dimensions.[1] The IUCR definition[2] used by crystallographers is:
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 CaCO3, sodium nitrate NaNO3 and iron borate FeBO3 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 is isostructural with gold(I) chloride
- Borazine is isostructural with benzene
- Indium(I) bromide is isostructural with β-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 usually have similar chemical structures. For example, methane, CH4, and the ammonium ion, NH4+, are isoelectric and are isostructural as both have a 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 salts.
References[edit]
- ^ Wells, A.F (1962). Structural Inorganic Chemistry (3rd. ed.). Oxford: Clarendon Press. ISBN 0-19-855125-8. p 182
- ^ IUCR Online Dictionary of CRYSTALLOGRAPHY, "Isostructural crystals"
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction