Types of Legands
Type of Legands:-
Legands are e- donors means nucleophile and their denticity depends on presence of lone pairs which can be co-ordinated.
Generally legands are anion or natural but sometimes they can be positively charged.
According to denticity there are 6 type of legands from unidentate to hexadentate.
- Unidentate or Monodentate:- One lone pair donor.
CS ->Thio Carbonyl
c) Negatively Charged:-
Oâ€‘ -NOO –-> Nitro
N- CO->Iso cyanoto
S-CN ->Thio cyanoto
N- CS ->Iso Thio cyanoto
Two lone pair donor
Note: All Bidentate have oxidation state -1.
And for (en) it is Zero.
Dien -> Diethylene triamine
Terpy --> Tripyridine
denticity means donation of lone pair.
nda --> nitrilodiacetato
4. Tetra dentate
Tetra dentate or Quadridentate:-
Trien --> Triethylene tetramine
5. Penta dentate
ethylene diamine triacetate
6. Hexa dentate
Hexa dentate:- EDTA
Ethylene diamine tetra acetato
In this more than one lone pair ore present at a time only one lone pair can be Co-ordinate their lone pair 3 or 4 membered ring is prepared which is highly unstable.
All ambidentate are pseudo
Flexi dentate:- All polydentate legand are flexi legand because they can show more than one type of denticity.
Ethylene diamine is bidentate legand but can also behave as unidentate.
It is non-cyclic legand but form cycle complex. Generally chilates are more stable than normal complexes but not always (because stabililty is decided by crystal filed theory).
It is a cycle legand which form cyclic complex. Macrocyclic are more stable than chilates.
- Hb and chloropyll are Macrocycle.
- All crown ethers are macrocycle.