3 Jun 2017

A Stable Monomeric SiO2 Complex with Donor-Acceptor Ligands: Foundational Implications of Lewis-Acid base interactions in Stabilizing SiO2

Literature Discussion

Submitted by Gary L. Guillet, Armstrong State University
Categories
Description: 

This module offers students in an introductory chemistry or foundational inorganic course exposure to recent literature work. Students will apply their knowledge of VSEPR, acid-base theory, and thermodynamics to understand the effects of addition of ligands on the stabilities of resulting SiO2-containing complexes. Students will reference results of DFT calculations and gain a basic understanding of how DFT can be used to calculate stabilities of molecules.

 
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File Questions for students18.86 KB
Learning Goals: 

Students should be able to:

  1. Apply VSEPR to determine donor and acceptor orbitals of the ligands

  2. Identify lewis acids and lewis bases

  3. Elucidate energy relationships

  4. Explain how computational chemistry is beneficial to experimentalists

  5. Characterize bond strengths based on ligand donors

Implementation Notes: 

Students should have access to the paper and have read the first and second paragraphs of the paper. Students should also refer to scheme 2 and table 2.

 

This module could be either used as a homework assignment or in-class activity. This was created during the IONiC VIPEr workshop 2017 and has not yet been implemented.

 
Time Required: 
50 min
Evaluation
Evaluation Methods: 

This LO was craeted at the pre-MARM 2017 ViPER workshop and has not been used in the classroom.  The authors will update the evaluation methods after it is used.

Creative Commons License: 
Creative Commons Licence

Comments

I'd recommend somewhere in the instructor notes (and maybe also in the student instructions) recommending using the pdf version of the paper. The online Full Text with figures particularly distorts Table 2, and I can see students get thrown off by the poor coordination of pictures above columns A-E with the actual columns A-E. 

The La = L1 nomenclature is very confusing, and it's the paper authors' fault, not the LO authors' fault for using both, but the LO authors could use a few words to help demystify this for the students.

The last couple of questions could probably be made a little clearer by adding redundancy...you could be explicit in each sub-question what you're asking them to compare, e.g., 8a. "Does the addition of D-A (Column C) stabilize SiO2 relative to free SiO2 (Column A)?" I could go either way on this. Forcing them to actually read and understand the table has its benefits (and is great for homework), but in-class, time is precious, and I don't want students thinking about the table, I want them thinking about the chemistry. Reasonable people will have different opinions here. 

The first question seems valuable (the students never get a Lewis Dot Structure of La and Lb in the paper!) but seems like it could be followed with a question asking them which of the three should be the strongest (and weakest) Lewis Base and why based on the LDSs. They're asked later which is the strongest donor, but that later question seems like begging the question, because they're presumably evaluating donor strengths from DelG values, when it makes more sense to me to have them make a call on what the strongest donor is first, and then ask whether the DelG values *corroborate* or *contradict* that earlier judgement. 

The ending left me wanting more...so D-A complexes stabilize SiO2, and do so more than just D complexes...what's the take-home? What should the students walk away with as the "big idea" from this paper/worksheet?

 

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