23 May 2017

Ligand based reductive elimination from a thorium compound

Literature Discussion

Submitted by Chip Nataro, Lafayette College

This literature discussion is based on a paper describing the ligand-based reductive elimination of a diphosphine from a thorium compound (Organometallics2017, ASAP). The thorium compound contains two bidentate NHC ligands providing an opportunity to discuss the coordination of these ligands. The ligand-based reduction is very subtle and would be challenging for students to pick up without some guidance. The compound undergoing reductive elimination also presents an excellent introduction into magnetic nonequivalence and virtual coupling. In addition, the compounds presented in this paper provide the opportunity to do electron counting on f-block compounds. 

File Questions for students2.71 MB
Learning Goals: 

Upon completing this LO students should be able to

  1. Use the CBC method to count electrons in the thorium compounds in this paper
  2. Describe the bonding interaction between a metal and a NHC ligand
  3. Discuss magnetic nonequivalency and virtual coupling
  4. Describe ligand-based reductive elimination and rationalize how it occurs in this system
Time Required: 
50 minutes
Evaluation Methods: 

This was developed after the semester in which I teach this material. I look forward to using it next fall and I hope to post some evaluation data at that point.

Creative Commons License: 
Creative Commons Licence


Used this in class for the first time today. Based on previous experience, I decided to split it up and give the students the first five questions to work on before class and the rest in class. I think that was a good idea, but I am not sure. The in class part went poorly. Take the question 6, set it aside and run, don't walk, run away. It confused the students beyond belief. We spent most of the class talking about it. Honestly, this makes me a little sad because we had discussed this topic in class previously, only a few weeks ago. I don't know exactly what happened here. Perhaps it was because it involved protons and my in class examples involved P-Se and P-F systems. Perhaps they just noded and played along with the material we talked about in class. I don't know. But if it went this poorly and I had previously talked about this concept, I can only imagine how it will go in a class where magnetic inequivalency is never mentioned. So, scrap question 6. It really hurts to say that because I think it is great work and a wonderful system to introduce this concept with. But I feel it did more harm than good at least in my class this fall. Just my two cents. Hopefully someone out there in VIPEr-land will have a different take on this.

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