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This paper discusses the synthesis and characterization of a novel compound of nitrogen. The pre-discussion assignment asks students draw a Lewis structure for the N5+ cation, and using the tools of group theory, conduct a normal mode vibrational analysis, comparing the results to the experimental Raman spectral data.
This LO was later added to a special VIPEr collection honoring the 2021 ACS National Award recipients in the field of inorganic chemistry. Karl O. Christe was the recipient of the M. Frederick Hawthorne Award in Main Group Inorganic Chemistry for major and original contributions to main group chemistry.
This LO was updated at the 2021 Summer Workshop with an expanded set of questions and an answer key. This LO is meant to be a replacement for the previous LO for this paper. Questions for the LO were created with the original LOs in mind.
| Attachment | Size |
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| N5cation_expandedproblemset_0.docx | 39.62 KB |
- When given a Lewis structure, students can accurately assign the geometry and point group.
- Students can predict the # of vibrational modes based on the molecular structure.
- Students can distinguish between IR and Raman-active vibrational modes.
- Students can assign the reducible representations of normal modes and reduce to their irreducible representations.
- Students can recognize the importance of polynitrogen compounds as high energy-density materials and the hazards associated with handling and researching polynitrogen compounds.
- Students can describe the overall aim of the work described in this paper.
This paper and accompanying discussion assignment is the basis of an in-class literature discussion after we cover the group theory tools for predicting the number of allowed Raman and IR normal modes of vibration for small molecules.
Update from 2021 workshop cohort: the expanded set of discussion questions can be implemented after the instructor has gone through the basics of group theory, normal modes, and how to use reducible and irreducible representations to find IR and/or Raman-active vibrational modes. The pre-lecture questions will help students gather basic knowledge that are required to work through the more challenging questions regarding the paper (students can use this Chem Libretext to review these concepts
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes/Normal_Modes). The in-lecture discussion questions are meant to allow students to implement that knowledge to determine the number of IR and Raman bands for N5+. Depending on the structure of the specific course, the pre-lecture questions can also be used as a knowledge check during class before diving into the reducible/irreducible representation problem.
Evaluation
Developed at the 2021 Workshop. When you use it, let us know how it turns out!