Dentate character

The dissociation rate constant is now composite, = k ik 2/k2- Following the first bond rupture (k 2) the competition between further bond rupture (/ , ) and reformation (Atj) which may lead to a small k j/k2 is the basic reason for the high kinetic stability of the chelate. The problem of complete dissociation is intensified when complexes of ligands of higher dentate character are examined. The situation is altered when the successively released donor atom(s) can be prevented from reattachment (see subject of accelerated substitution). 

Dentate character is a property of a ligand representing a number of... 

In the case of [Co(NH3)6]Cl3, ammonia, NH3 the ligand contains one donor atom (N). Hence its dentate character is one and is classified as a monodentate ligand. Similarly, chloro (Cl ) is an anionic, monoatomic and monodentate ligand, while hydroxo (OH ) is a diatomic, monodentate and anionic ligand. Aquo (OH2) represents a neutral triatomic monodentate ligand. A few popular Hgands and their characteristics are shown in Figure 5. 

Ligand — An electron-pair donor species, commonly an anion or a neutral molecule that can form one or several bonds, involving highly covalent character, with metal species. A ligand with a single donor group is usually called unidentate, whereas the terms bidentate, tri-dentate, tetradentate, pentadentate, and hexadentate are commonly used to indicate the number of bonds that... 

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