Linkage isomerism

Linkage isomerism

Linkage isomerism is the existence of co-ordination compounds that have the same composition differing with the connectivity of the metal to a ligand.

History

The first reported example of linkage isomerism had the formula [Co(NH3)5(NO2)] Cl2. The cationic cobalt complex exists in two separable linkage isomers. In the red-coloured isomer, the nitro ligand is bound through nitrogen. In the yellow linkage isomer, the nitrito is bound through one oxygen atom. The O-bonded isomer is often written as [Co(NH3)5(ONO)] 2+. Although the existence of the isomers had been known since the late 1800’s, only in 1907 was the structural difference explained. [ Werner, A. “Über strukturisomere Salze der Rhodanwasserstoffsäure und der salpetrigen Säure” Berichte der deutschen chemischen Gesellschaft 1907, volume 40, 765-788. DOI: 10.1002/cber.190704001117] It was later shown that the red isomer converted to the yellow isomer upon UV-irradiation. In this particular example, the formation of the nitro isomer (Co-NO2) from the nitrito isomer (Co-ONO) occurs through the rearrangement of the molecular structure. Thus, no bonds are broken during isomerization.

cope of linkage isomerism

Typical ligands that give rise to linkage isomers are:
*thiocyanate, SCN-
*selenocyanate, SeCN-
*nitrite, NO2-
*sulfite, SO32-

Examples of linkage isomers are violet-colored [(NH3)5Co-SCN] 2+ and orange-colored [(NH3)5Co-NCS] 2+. The isomerization of the S-bonded isomer to the N-bonded isomer occurs intramolecularly. [Buckingham, D. A.; Creaser, I. I.; Sargeson, A. M. "Mechanism of Base Hydrolysis for CoIII(NH3)5X2+ Ions. Hydrolysis and Rearrangement for the Sulfur-Bonded Co(NH3)5SCN2+ Ion" Inorganic Chemistry (1970), volume 9, pages 655-61.]

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • coordination compound — Chem. complex (def. 10). Also called coordination complex. * * * ▪ chemistry Introduction  any of a class of substances with chemical structures in which a central metal atom is surrounded by nonmetal atoms or groups of atoms, called ligands… …   Universalium

  • Coordination complex — Cisplatin, PtCl2(NH3)2 A platinum atom with four ligands In chemistry, a coordination complex or metal complex, is an atom or ion (usually metallic), bonded to a surrounding array of molecules or anions, that are in turn known as ligands or… …   Wikipedia

  • Complex (chemistry) — The term complex in chemistry is usually used to describe molecules or ensembles formed by the combination of ligands and metal ions. Originally, a complex implied a reversible association of molecules, atoms, or ions through weak chemical bonds …   Wikipedia

  • Ligand — This article is about ligands in inorganic chemistry. For ligands in biochemistry, see Ligand (biochemistry). For other uses, see Ligand (disambiguation). Cobalt complex [HCo(CO)4] with five ligands In coordination chemistry, a ligand is an ion… …   Wikipedia

  • Thiocyanate — (also known as sulphocyanate or thiocyanide or rhodanide) is the anion, [SCN] −. Common compounds include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called… …   Wikipedia

  • Dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) — Dichlorotetrakis(dimethyl sulfoxide) ruthenium (II) …   Wikipedia

  • Thiocyanate — L anion thiocyanate Les thiocyanates aussi connus sous les noms de sulphocyanates, thiocyanures et rhodanures[1] sont des composés intégrant l anion [SCN]− qui est la base conjuguée de l acide thiocyanique (HSCN). Les sels incolores …   Wikipédia en Français

  • Isomer — This article is about the chemical concept. For isomerism of atomic nuclei, see nuclear isomer. In chemistry, isomers (from Greek ἰσομερής, isomerès; isos = equal , méros = part ) are compounds with the same molecular formula but different… …   Wikipedia

  • carbohydrate — /kahr boh huy drayt, beuh /, n. any of a class of organic compounds that are polyhydroxy aldehydes or polyhydroxy ketones, or change to such substances on simple chemical transformations, as hydrolysis, oxidation, or reduction, and that form the… …   Universalium

  • Amino acid — This article is about the class of chemicals. For the structures and properties of the standard proteinogenic amino acids, see Proteinogenic amino acid. The generic structure of an alpha amino acid in its unionized form …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”