21 Feb 2017

Diverting Wilkinson's Catalyst: Critical Analysis of a Literature Paper

Literature Discussion

Submitted by Matt Whited, Carleton College
Categories
Description: 

This LO is a problem-set-style literature discussion that leads students through a critical analysis of an interesting but flawed paper from the recent chemical literature.  Students use the questions to help them work through the paper prior to class, providing plenty of raw material for an in-class discussion about various aspects of the work from a mechanistic organometallic perspective.  The questions help students critically analyze substrate tables, spectroscopic data, and computational results from DFT.

Learning Goals: 
  • Students will be able to pull out important mechanistic information from substrate tables in an organometallic paper
  • Students will be able to use knowledge of organometallic mechanisms and organic chemistry to rationalize findings in a catalysis paper
  • Students will be able to use knowledge of spectroscopy, particularly NMR, to understand structure and bonding arguments in an organometallic paper
  • Students will critically analyze a paper and learn to feel comfortable questioning assertions by authors, including the major findings of a paper
Implementation Notes: 

I had students prepare answers to these questions ahead of class and bring the answers with them.  To add incentive, I collected them as a homework assignment (though I graded some of the harder ones fairly leniently).  The questions helped prepare them for a class discussion of the paper, which I led with a few slides containing information from the paper and some other useful tidbits (I am happy to send those to you if you like, just contact me).

Time Required: 
1-2 hours student prep (reading paper); 45 minutes in class discussion
Evaluation
Evaluation Methods: 

Graded problems students turned in.

Informal evaluation during discussion.

Evaluation Results: 

Graded assignments: mean of 84, std dev of 12, so a fairly broad range of understandings

Informal: Students really enjoyed getting to evaluate published work critically and were quite engaged in discussions, which helped to bring some of the students who didn't understand the paper as well up to speed.  After the paper, students have felt much more comfortable questioning what is stated in papers, particularly if little or no support is given.

I will definitely use this again!  Unfortunate to find a paper with several important oversights in the literature, but it is a good learning opportunity.

Creative Commons License: 
Creative Commons Licence

Comments

This is a really interesting lit discussion, and quite challenging for me. I have a few questions and suggestions.

1. I like that you start out by asking them to identify the bases because that was the first thing I did when I started reading the paper. (I had to look them up.)

2. Question 2 asks "What is the general role of base?" It would be helpful to have some context: "...in organic reactions? ...in catalysis ...in this reaction?" I got confused by what the authors said. They wrote that the first few bases "just play a spectator role" (not a Lewis base role?) and "a stronger base and drastic reaction conditions would be required to deprotonate the stronger Rh[BOND]H bonds featured in the resulting neutral dihydride intermediates." I did see in Table 1 that something very different was happening with bases 12 and 13, but I didn't think the conditions were "drastic." So I got confused. Maybe you could give a little more guidance here?

3. For 2a, I agree that the strong base may be reacting with the acidic terminal alkyne. That's a good thing for students to learn/know.

4. I love NMR, but I needed more help with the interpretation. Your HINTS are great. I was fine with the hydrides in (a) because of your last hint about trans couplings through metals. I was wondering about the absence of Rh coupling, but the peaks were broad so I let that go. I was confused by how they used the terms "trans" and "cis" in (b). Trans and cis to what? I can see that there is only one P trans to an H, but I was very uncertain if that's what they meant. Could you add a clarifying statement? 

5. I could see that Ptrans was very broad, but students may need help seeing that.

6. In question 4, you're missing a subscript 3 for the phosphine.

7. Could you add a hint to question 6? Something like "Consider the energies they find." That may make it "too obvious" for you, but I wasn't sure where to go with the question.

8. In question 7, if you want the students to consider the data you included in your answer (from the SI), then you will need to point them there. 

Changes made! Good job, Matt.

 

 

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