Inorganic Reaction Mechanism part(II)

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Inorganic Reaction Mechanism part(II) :


Associative Reaction:
The M-Y bond is fully formed before M-X begins to break. 
   It involves a step in which a intermediate is formed with a higher coordination number than the original complex.

This mechanism plays a role in many reaction of squarplaner Pt(II),Pd(II),Ni(II)and Ir(I) d8 complexes. Example :
The exchange of 14CN with the ligands in the squareplanar complex such as Tetracyanonickel(II) ion the 1st step is the coordination of a ligand to the complex shown given bellow


The energy profile diagram  of this reaction is shown bellow



Dissociative Reaction:

 The M-X bond is fully broken before the M-Y bond is begins to form
    It is a reaction sequence in which an intermediate of reduced coordination number is formed by the daparture of leaving group.

Here MLn is true intermediate that can,  in principle be detected (or isolated) for example the substitution  of hexacarbonyltugsten by phosphine take places by dissociating of CO from complex



The energy  profile diagram  of this reaction is shown as bellow

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