This document discusses acid and base hydrolysis in octahedral complexes. It covers factors that affect the rate of acid hydrolysis, including the charge on the complex, steric hindrance effects, and the strength of the leaving group. A higher positive charge, more steric hindrance, or stronger metal-leaving group bond each decrease the rate of acid hydrolysis according to first-order kinetics through a dissociative SN1 mechanism. Base hydrolysis of octahedral complexes can proceed by either associative SN2 or dissociative SN1 pathways depending on conditions.

1. ACID AND BASE
HYDROLYSIS IN
OCTAHEDRAL COMPLEXES
SUBMITTED BY : ALTAF HUSSAIN
M.SC 1ST SEMESTER
( 2020-2021 )
DEPARTMENT OF CHEMISTRY
S.P.C GOVERNMENT COLLEGE ,
AJMER

2. CONTENTS
 INTRODUCTION
 HYDROLYSIS REACTIONS
 ACID HYDROLYSIS IN OCTAHEDRAL COMPLEX
 FACTORS AFFECTING ACID HYDROLYSIS
1 CHARGE ON THE COMPLEX
2 EFFECT OF STERIC HINDRANCE
3 EFFECT OF LEAVING GROUP
 BASE HYDROLYSIS OF OCTAHEDRAL COMPLEXES

4. TWO TYPE

5. Example =
Order = first order kinetics
The rate of the reaction would be dependent only on the
concentration of the complex.

6. SN1

8. 1. Charge on the complex
An increase in the positive charge on the complex
make M-L bond more stronger due to good
overlapping between metal & ligand.
The decrease in reaction rate is observed as the charge
of the complex increases, a dissociative nucleophilic
substitution SN1 process seems to be operative.
Fast
slow

9. 2.Effect of crowding ( steric hindrance )
An increase in the steric crowding around the metal ion
preferably favors a dissociative nucleophilic substitution
SN1 mechanism
For example, when we consider the [Co(NH3)5Cl]2+
complex, the NH3 molecule in [Co(NH3)5Cl]2+ complex
ion are replaced by ethylenediaamine (en) the rate of
acid hydrolysis of the complex is decreases.

10. 3.Effect of leaving group
the strength of the M-L bond is directly proportional to the
basicity of the leaving group, the rate of acid hydrolysis decreases
with the increase in the strength of M-X bond i.e. with the
increase of basicity of the leaving group. This indicates that the
rate determining step in the acid hydrolysis involve the
dissociation (i.e. SN1 mechanism )
It has been observed that the reactivity of leaving group decreases in
the order of
Example=

11. Table for Factors affecting acid hydrolysis:
1