Thursday, January 17, 2019

18 Electron rule

18 electron rule is to account the stability of the organomettalic complex. 
It can be calculated by adding group number of central metal atom and total number of electron contribution of ligand atom.


 Eg:Cr(CO)6

6+2*6=18
Here central metal atom has the group number=6 and each CO ligand contribute 2 electron.

Metal Complexes also called as coordination complex is the chemical structure which contains central metallic atom, bonded with number of surrounding molecules are also called as ligands.
The atom in the ligand which is directly connected with metal atom is called as donaratom.


Applicability




The rule usefully predicts the formulae for low-spin complexes of the Cr, Mn, Fe, and Co triads. Well-known examples include ferrocene, iron pentacarbonyl, chromium carbonyl, and nickel carbonyl.

All metal complexes are not following 18 electron rules but there are some selected low spin metal complexes follow the this.

Ligands in a complex determine the applicability of the 18-electron rule.

Ligands are the atoms or molecules which bind the central atom to form coordination complexes. There are lots of applications of ligands in coordination chemistry and bio chemistry and applied biology.



Calculation methods:



Some other examples:







No comments:

Post a Comment