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Sibrina Collins, The Charles H. Wright of Museum of African American History
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Crystal Field Splitting and the F Orbitals

Colleagues,

I love crystal field theory, but I would like to try and extend this idea to the f-orbitals. We know how the d-orbitals split in an a variety of environments, but how do the f orbitals split?  I want to develop an assignment for my students where they can use their knowledge from the d-orbitals to think about how the f-orbitals would split. Any ideas? I know CFT is not as important for the lanthanides, but I think it could be an interesting extension to what students typically learn about CFT.

Chip Nataro, Lafayette College
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My guess is that you ask a fairly difficult question. With d complexes octahedral is a pretty good starting point for geometry. I don't know what you would use as your basis geometry for lanthanides. That comes completely from my ignorance, hopefully someone far smarter than me will have some insight. It is an interesting idea, but it may not be as simple as one would hope.
Sibrina Collins, The Charles H. Wright of Museum of African American History
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Chip, yep this is a challenging question. I need to find a geometry as a starting point and go from there. I will work on some ideas.

Sibrina 

Joanne Stewart, Hope College
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You really need to move to the actinides before you can find much evidence of crystal-field splitting. The 4f orbitals are just too darn small. There was some work done at Lawrence Berkeley Labs (I think...probably in the early 80's) where they doped crystals with actinide elements and looked at the impact of the crystal field on the f orbitals. I'll see what I can find.
Joanne Stewart, Hope College
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Oh, and I forgot to add that they can't be treated as spin-only systems. You have to use spin-orbit coupling to calculate their electronic states. Norm Edelstein and his group at LBL did much of this work.
Clifford Rossiter, SUNY Potsdam
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Dear Fellow Vipers,

I have to concur with Dr. Stewart. The f orbits of the lanthanides are notoriously insensitive to ligand effects. It would actually be interesting to demonstrate this property by showing how d-splitting can change the fluorescent properties of transition metals through ligand metal interactions, while ligands do not significantly modulate the fluorescence of the lanthanides.

Sincerely

Cliff

 

Sibrina Collins, The Charles H. Wright of Museum of African American History
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Dear Colleagues,

Thanks for the great dialog! Maybe my conversation with my students should be why CFT doesn't work for the f-orbitals? (smile) Joanne, let me know what you find.

Sibrina

Sibrina Collins, The Charles H. Wright of Museum of African American History
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Ok, I have found some good internet resources on the topic, showing how the f-orbitals split in an octahedral environment. See the link below that could be used to extend the discussions on CFT. Let me know your thoughts on this resource.

http://wwwchem.uwimona.edu.jm:1104/courses/OctCFT_FOrbs.html

 

Sibrina 

Adam R. Johnson, Harvey Mudd College
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There are 2 parts to this question... the theoretical predictions, from symmetry, and the actual results, from experiment.  You could certainly predict a splitting of the f-orbitals given a geometry. Whether it means anything.... I'll leave that to a real Ln/Ac chemist. 

Another problem is that there are at least 2 "simple" ways to represent the f-orbitals, and they may have different symmetries.  I know there is a J. Chem. Educ. article (I think; maybe IC) on this topic (conveniently in my office 5000 miles away) written before 1993, but I can't find it right now. One way was more axial and one way was oriented differently with more tori, I think.

Adam R. Johnson, Harvey Mudd College
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I found a possibly useful article by Kettle, who is one of my favorite bonding theory authors anyway! 

S. F. A. Kettle and A. J. Smith, J. Chem. Soc. A, 1967, 688-692,DOI: 10.1039/J19670000688

 

 

Sibrina Collins, The Charles H. Wright of Museum of African American History
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Thanks Adam!

Sibrina Collins, PhD College of Wooster

Ahmad Amiri, pHD student of Inorganic chemistry , pHD Student
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You can find your answer in the book entitled with :  "ligand field theory and it's applications" by the Authors: B. N. Figgis and M. A. Hitchman published by wiley-VCH.

the chapter 4 of this book explain it.