Jahn teller effect
- 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