About Jahn Teller Effect in octahedral chemistry

1. Jahn-Teller Effect
Presented by
Meghnath Kalita
Msc 2nd semester
Roll no. 06

2. Contents :
•History
•Introduction
•Jahn - Teller effect
•Z out and Z in distortion
•Examples
•Static and Dynamic JT distortion
•Conclusion
•References

3. History
Hermann Arthur
Jahn(born 31 May
1907, Colchester,
England; d. 24 October
1979 Southampton)
was an English scientist
of German
origin.With Edward
Teller, he identified
the Jahn–Teller effect.
Edward Teller (Hungarian: Teller Ede; January
15, 1908 – September 9, 2003) was
a Hungarian-American theoretical
physicist who is known colloquially as "the
father of the hydrogen bomb", although he
claimed he did not care for the title. He made
numerous contributions
to nuclear and molecular
physics, spectroscopy (in particular the Jahn–
Teller and Renner–Teller effects), and surface
physics.

4. Jahn-Teller Theorem
Jahn-Teller theorem states that any non linear molecule in
a degenerate electronic state will distorted so as to remove
that degeneracy
Or, to put in a different way, when a degenerate set of
orbital is occupied asymmetrically then a distortion will
occur which will remove the degeneracy of the orbital.
*asymmetrically filled non linear complexes shows Jahn Teller
distortion
*to remove degeneracy

5. • If the ligand is present in Z-axis or axial axis, it will
expand and bond length is increased when move
toward outside is called Z-out distortion and the
reversed is called Z-in distortion .
• The distortion of a regular octahedron, to
extension along the Z-axis and comparison in x
and y axes(Z-out) lowers the energy of eg
orbital and increased the energy of eg
orbital. Therefore, if one or three electrons
occupy the eg orbital as in d4(HS), d7(LS) and d9
complexes shows huge distortion and
energetically advanced.
dx
2
-y
2
dz
2

6. Z-out
Z-in
• Z-out is favourable because there is two bond increases in bond length
• Z-out is Lower in energy
• Z- is the molecular axis

7. • In z-out distortion , the repulsion between
electrons between metal orbital and ligand
orbital is decreased due to elongation of z axis
and ligand in z axis gives a repulsion with metal
electrons. so, the orbital is lower in energy
and also
• For z-in distortion the repulsion between
electrons of MO is increases because they are
come closer to each other and repulsion is high
so, is higher in energy
• The lower the energy more stable the complex
dz
2
dxz,dyz
dz
2

8. Molecular orbital diagram of Jahn-Teller distortion
eg
t2g
dxz ,dyz
dxz,dyz
dxy
dxy
dz
2
dz
2
dx
2
-y
2
dx
2
-y
2
-2/3
2/3
-1/3
1/3
1/2
1/2
-1/2
-1/2
a) Z-in distortion b) Z-out distortion
δa
δa
δb
δb
Δ0
Δ0
δ1
δ1
δ2
δ2
δ3
δ3
δ4 δ4

9. Static and dynamic Jahn-teller distortion
Static Jahn-Teller distortion:
•Complexes having measureable bond length differences are the
examples of static Jahn Teller distortion
• SJTD shows at all condition
•Complexes having asymmetric filling of eg shows SJTD
Dynamic Jahn-Teller distortion :
•A Jahn-Teller distortion Can hop from one orientation to another,
give rise to dynamic Jahn-Teller distortion
•Occurs only at low temperature

10. Conclusion
To remove degeneracy in a non linear complex
Asymmetrically filled
Degeneracy is removed either by elongation or
compression
Elongation is favorable due to lesser in energy
Lower the energy more stable the complex
Detected by X-ray crystallography and electronic Spectra
Static and Dynamic Jahn–Teller distortion

11. Reference
•Inorganic chemistry-Principle of structure and
reactivity-James E. Huheey, Ellen.A Keiter, Richard
L.Keiter, Okhil.K Medhi-Fourth edition- Pearson -
477—481.
•Inorganic chemistry –Shiver and Atkins’— Atkins,
Overtone, Rourke, Weller, Armstrong,--fifth
edition—Oxford--

12. Thank you