17 Feb 2011

Ligand Field Theory in Coordination Complexes- In Class Exercise

In-Class Activity

Submitted by Sheila Smith, University of Michigan- Dearborn
Categories
Description: 

This is an In class exercise on the subject of Ligand Field theory.  It reviews nomenclature and introduces ideas of ligand field splitting and spin in transition metal complexes.  It includes both a worksheet for classroom use, a worksheet key which includes some information not on the student worksheet .

AttachmentSize
PDF icon LFT_ICE_ worksheet.pdf35.14 KB
Learning Goals: 

A student should be able to name a coordination complex based on a structure including the determination of the metal oxidation state. A student should be able to determine the number of d electrons in a coordination complex. A student should be able to draw an orbital energy diagram for a metal ion in an octahedral ligand field. A student should be able to qualitatively evaluate whether a coordination complex will be high spin or low spin based on trends in metal size, oxidation state and ligand field strength (position of the ligand in the spectrochemical series). A student should be able to quantitatively evaluate whether a complex will be high spin or low spin based on ligand field stabilization energy (given appropriate values for DeltaO and Pairing energy. A student should be able to determine qualitatively whether a complex is paramagnetic or diamagnetic. A student should be able to determine quantitatively the spin-only contribution to the magnetic moment of a complex.

Equipment needs: 

N/A

Time Required: 
30-45 minutes
Evaluation
Evaluation Methods: 

Students turn in completed worksheets at the end of the class period. Students are tested on similar written exam material.

Evaluation Results: 

The best evaluation of this exercise is the richness of the discussion that it generates. In allowing students to connect previously learned material to new ideas of spin in complexes, the exercise builds an understanding of the complexities of configurations in coordination complexes.

Creative Commons License: 
Creative Commons Licence

Comments

Chip-

 

It seems like you are evaluating the two LOs (IC activity and Key) independently, which may be an issue with the way I set it up.  Since this is an in class activity, it relies on discussion (from both faculty and student) to make the students consider both the high spin and the low spin possibilities.  This is why all that extra data was included in the key. 

Sheila SmithAssociate Professor of ChemistryUniversity of Michigan- Dearborn313-583-6399(office)734-788-8144 (cell)  

Perhaps I should just add an implementation note? 

 

Sheila SmithAssociate Professor of ChemistryUniversity of Michigan- Dearborn313-583-6399(office)734-788-8144 (cell) 

I used this in my class after my MO unit and as an introduction to my magnetism unit.  We have done MO diagrams for transition metal complexes and the spectrochemical series.  This was a nice 20-25 minute exercise that nicely ended the unit.  One question that I got during the exercise is worth noting, and definitely worth adding to the exercise if you were to try it.  The question was whether or not the Mn complex would be expected to distort from octahedral geometry (Jahn-Teller).  I had students also report their answers to that question during the in-class exercise. I'll put my answer in the comments on the answer key page.

Nice summative way for me to end my unit.

thanks for posting this,

Adam

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