Ligands-definition-examples-types in co-ordination chemistry .

Ligand definition in co-ordination chemistry

In co-ordination chemistry, the cation to which one or more neutral molecules or ions are co-ordinated is called centralmetal cation, while the molecules or ions so attached are called Ligand.

         For examples , CN^– , Cl^– , CO  , H₂O  NH₂–NH₂ etc.

Ligand examples in co-ordination chemistry

There are three types of ligands depending on the nature of charge are known . Such as cationic ligand, anionic ligand and neutral ligand.  

Ligand types in co-ordination chemistry

There are different  types of ligands  are known depending on their function  in co-ordination  with the central metal ion in co-ordinationchemistry .

Such as ambident ligands , flexidentate ligands , classical ligands, non-classical ligands, chelating ligand, π-acid ligand etc.

Ambident ligands.

There are few ligands which contain more than one donor atom, but they can use only one donor atom at once in the formation of complex compound, these type of ligands are called Ambident ligands.

There are two types of ambident ligand, namely, mono dentate ambident ligand  and bidentate ambident ligand.

When a mono dentate ambident ligand ( such as nitrite ion ) ,is attached with different central metal ion , it uses either ‘N’ atom or ‘ O ‘ atom as a donor atom .

Similarly, when a bidentate ambident ligand ( such as dithio oxalate ion ), is attached with different central metal ion, it uses either both the ‘O’ atom or both the ‘S ‘ atom together as a donor atom.

Flexidentate ligands

There are few ligands in co-ordination chemistry which have two or more donor atoms. 

But ,they do not use their entire donor atom at once in the formation of co-ordination  compound that is in co-ordination with central metal ion .

They use their different donor atom with different metal ion to form co-ordinate bond . Such types of ligands are called flexi dentate ligands.

For example, Cysteine, a tri-dentate ligand with three different donor atoms ( S, N, O ) act as a di dentate ligand in three different way [ when it uses S,N  , N,O  and S,O  atom separately ]

So, Cysteine is a flexi dentate ligand.

Similarly, there are many other poly dentate ligands those are behaved as a flexi dentate ligand.

Such as, EDTA , a poly dentate ligand , but in some cases it uses as a penta dentate or tetra dentate ligand. So, EDTA is also a flexi dentate ligand.

There are another two types of ligands are known which are, classical ligands and non-classical ligands .

( I ) Classical ligands :  Classical ligands are those ligands which can co-ordinate with the central metal ion by using their lone pair of electrons .

 For examples  CO , CN ^– , F ^–, Cl ^– , OH ^–, H₂O , NH₃ etc .

 (II )  Non-classical ligands : There are few ligands which uses their electron-pair of pi bond in the formation of co-ordinate bond with the central metal ion , these type of ligands are called Non-classical ligands.

For examples  C₂H₄ , C₆H₆ , C₅H₅ – [ cyclo penta dienyl anion ] etc.

Summary :

• Ligand definition in co-ordination chemistry
• Ligand examples in co-ordination chemistry 
• Ligand types in co-ordination chemistry
• What is ambidentate ligands ? 
• What is flexidentate ligands ? 
• What is classical ligands ? 
• What is non-classical ligands ? 

Complex compound definition in chemistry .