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In chemistry, linkage isomerism or ambidentate isomerism is a form of structural isomerism in which certain coordination compounds have the same composition but differ in which atom of the ligand is bonded to the metal. Typical ligands that give rise to linkage isomers are: cyanide, CN − – isocyanide, NC −; cyanate, OCN − – isocyanate ...
A classic example of a polydentate ligand is the hexadentate chelating agent EDTA, which is able to bond through six sites, completely surrounding some metals. The number of times a polydentate ligand binds to a metal centre is symbolized by " κ n ", where n indicates the number of sites by which a ligand attaches to a metal.
In coordination chemistry, denticity (from Latin dentis 'tooth') refers to the number of donor groups in a given ligand that bind to the central metal atom in a coordination complex. [1] [2] In many cases, only one atom in the ligand binds to the metal, so the denticity equals one, and the ligand is said to be unidentate or monodentate.
Chelation (/ k iː ˈ l eɪ ʃ ən /) is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom.
In DNA-ligand binding studies, the ligand can be a small molecule, ion, [1] or protein [2] which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces.
This ligand–metal–ligand geometric parameter is used to classify chelating ligands, including those in organometallic complexes. It is most often discussed in terms of catalysis , as changes in bite angle can affect not just the activity and selectivity of a catalytic reaction but even allow alternative reaction pathways to become accessible.
Thiocyanate can bind metals at either sulfur or nitrogen — it is an ambidentate ligand. Other factors, e.g. kinetics and solubility, sometimes influence the observed isomer. For example, [Co(NH 3) 5 (NCS)] 2+ is the thermodynamic isomer, but [Co(NH 3) 5 (SCN)] 2+ forms as the kinetic product of the reaction of thiocyanate salts with [Co(NH 3 ...
For example, ferrocene, [(η 5-C 5 H 5) 2 Fe], has two cyclopentadienyl ligands giving a hapticity of 5, where all five carbon atoms of the C 5 H 5 ligand bond equally and contribute one electron to the iron center. Ligands that bind non-contiguous atoms are denoted the Greek letter kappa, κ. [7] Chelating κ2-acetate is an example.