![Example 3:
Consider the reaction given below:
(i) [R-C-O-Co (NH3)5]2+ [Cr(H2O)6]2+
oxidant reductant
[(H2O)5Cr-O O-Co(NH3)5]4+
C
R
O
Evidently we can say
that this reaction
follows inner sphere
mechanism. Because
bridging of complex
ion have taken place.
COOR is the bridge
between the oxidant and
the reductant](https://image.slidesharecdn.com/innerspheremechanism-210901090340/85/Inner-sphere-mechanism-3-320.jpg)
![[(H2O)5Cr-O O-Co(NH3)5]4+ hydrolysis [Co(NH3)5(H2O)]2+ +
C [(H2O)5-Cr-O-C-R]2+
R O
Rate of reaction is
increased if R is
unsaturated or
conjugated.
Transfer of
bridging ligand have
taken place.
Reaction is
fast when
compared to
reaction (a)](https://image.slidesharecdn.com/innerspheremechanism-210901090340/85/Inner-sphere-mechanism-4-320.jpg)
Inner sphere mechanism
- 2. Main characteristics of inner sphere mechanism. ▪ In order that electron transfer occurs, one of the complexes should be inert and other one labile. ▪ The inert complex ion should have a ligand capable of bridging both the complex ions during the formation of intermediate. ▪ Faster than similar reactions occurring through outer sphere mechanism. ▪ Rate of electron transfer increases if the bridging ligand has unsaturation or extended conjugation in its structure. ▪ Rate increases with increase in nucleophilic character of bridging ligand. ▪ Sometimes along with electron transfer , the bridging ligand is also transferred from one complex ion to other. But it’s always not necessary. ▪ The transfer or nontransfer of bridging ligand depends upon the relative stabilities of the products that are possible from the bridged intermediate.
- 3. Example 3: Consider the reaction given below: (i) [R-C-O-Co (NH3)5]2+ [Cr(H2O)6]2+ oxidant reductant [(H2O)5Cr-O O-Co(NH3)5]4+ C R O Evidently we can say that this reaction follows inner sphere mechanism. Because bridging of complex ion have taken place. COOR is the bridge between the oxidant and the reductant
- 4. [(H2O)5Cr-O O-Co(NH3)5]4+ hydrolysis [Co(NH3)5(H2O)]2+ + C [(H2O)5-Cr-O-C-R]2+ R O Rate of reaction is increased if R is unsaturated or conjugated. Transfer of bridging ligand have taken place. Reaction is fast when compared to reaction (a)