Sarcosine, a glycine transporter type 1 inhibitor and an N-methyl-D-aspartate (NMDA) receptor co-agonist at the glycine binding site, potentiates NMDA receptor function. Structurally similar to sarcosine, N,N-dimethylglycine (DMG) is also N-methyl glycine-derivative amino acid and commonly used as a dietary supplement. The other Co(III) atom is coordinated by four nitrogen atoms of two cis nonplanar ligands, dmg 2−, dmgH −, and two oxygen atoms of the other dmg 2− and dmgH − ligands. There are three N-O bridged ligands namely two dmg 2− and one dmgH − between two Co(III) atoms. A free molecule of dmgH 2 and a molecule of CH 3 OH are also found in the crystal lattice.

• Dmg Ligand Formula
• Dmg Chelating Ligand

Nickel;N-(Z)-3-nitrosobut-2-en-2-ylhydroxylamine C8H16N4NiO4 CID 5475696 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.

Denticity refers to the number of donor groups in a single ligand that bind to a central 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 monodentate (sometimes called unidentate). Ligands with more than one bonded atom are called polydentate or multidentate. The word denticity is derived from dentis, the Latin word for tooth. The ligand is thought of as biting the metal at one or more linkage points. The denticity of a ligand is described with the Greek letter κ ('kappa').^[3] For example, κ⁶-EDTA describes an EDTA ligand that coordinates through 6 non-contiguous atoms.

Denticity is different from hapticity because hapticity refers exclusively to ligands where the coordinating atoms are contiguous. In these cases the η ('eta') notation is used.^[4]Bridging ligands use the μ ('mu') notation.^[5][6]

Classes[edit]

Polydentate ligands are chelating agents^[7] and classified by their denticity. Some atoms cannot form the maximum possible number of bonds a ligand could make. In that case one or more binding sites of the ligand are unused. Such sites can be used to form a bond with another chemical species.

• Bidentate (also called didentate) ligands bind with two atoms, an example being ethylenediamine.

Dmg Ligand Formula

• Tridentate ligands bind with three atoms, an example being terpyridine. Tridentate ligands usually bind via two kinds of connectivity, called 'mer' and 'fac.' 'fac' stands for facial, the donor atoms are arranged on a triangle around one face of the octahedron. 'mer' stands for meridian, where the donor atoms are stretched out around one half of the octahedron. Cyclic tridentate ligands such as TACN and 9-ane-S3 bind in a facial manner.
• Tetradentate ligands bind with four donor atoms, an example being triethylenetetramine (abbreviated trien). For different central metal geometries there can be different numbers of isomers depending on the ligand's topology and the geometry of the metal center. For octahedral metals, the linear tetradentate trien can bind via three geometries. Tripodal tetradentate ligands, e.g. tris(2-aminoethyl)amine, are more constrained, and on octahedra leave two cis sites (adjacent to each other). Many naturally occurring macrocyclic ligands are tetradentative, an example being the porphyrin in heme. On an octahedral metal these leave two vacant sites opposite each other.
• Pentadentate ligands bind with five atoms, an example being ethylenediaminetriacetic acid.
• Hexadentate ligands bind with six atoms, an example being EDTA (although it can bind in a tetradentate manner).
• Ligands of denticity greater than 6 are well known. The ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) and diethylene triamine pentaacetate (DTPA) are octadentate. They are particularly useful for binding lanthanide ions, which typically have coordination numbers greater than 6.

Stability constants[edit]

In general, the stability of a metal complex correlates with the denticity of the ligands, which can be attributed to the chelate effect. Polydentate ligands such as hexa- or octadentate ligands tend to bind metal ions more strongly than ligands of lower denticity, primarily due to entropic factors. Stability constants are a quantitative measure to assess the thermodynamic stability of coordination complexes.

See also[edit]

External links[edit]

• EDTA chelation lecture notes. 2.4MB PDF - Slide 3 on denticity

References[edit]

1. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'denticity'. doi:10.1351/goldbook.D01594
2. ^von Zelewsky, A. 'Stereochemistry of Coordination Compounds' John Wiley: Chichester, 1995. ISBN047195599X.
3. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'κ (kappa) in inorganic nomenclature'. doi:10.1351/goldbook.K03366
4. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'η (eta or hapto) in inorganic nomenclature'. doi:10.1351/goldbook.H01881
5. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'bridging ligand'. doi:10.1351/goldbook.B00741
6. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'µ- (mu) in inorganic nomenclature'. doi:10.1351/goldbook.M03659
7. ^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the 'Gold Book') (1997). Online corrected version: (2006–) 'chelation'. doi:10.1351/goldbook.C01012

If you have not registered for a membership,
please complete the registration procedure.

Members-only Contents

A variety of technical information, including industry trends, advanced machining examples, next-generation technology and solutions, are provided exclusively for the members.

MyPage

MyPage allows the members to create their own page, where they can save information of their interest or their favorite contents posted on the DMG MORI website.

Membership privileges

The Web members have the privilege of receiving special offers.

Dmg Chelating Ligand