Submitted by Kyle Grice / DePaul University on Fri, 11/11/2016 - 19:28
Additional Authors
Fabiola BL / The Cooper Union for the Advancement of Science and Art
Marion Cass / Carleton College
My Notes
Categories
Prerequisites
General Chemistry
Organic Chemistry
Corequisites
No Corequisites
Course Level
Upper Division/Graduate
Topics Covered
Bonding models: Discrete molecules
Chemical literature
Descriptive chemistry
Electronic structure
Group theory & applications
Molecular structure
Physical methods / analytical techniques
Symmetry
Subdiscipline
Coordination Chemistry
Molecular Structure and Bonding
Organometallic Chemistry
Spectroscopy and Structural Methods
Description

Literature discussion about the first examples of molecular hydrogen complexes isolated by Gregory J. Kubas in the early 80s. The questions are divided into groups with two levels of difficulty.

The more basic group of questions includes topics on:

1)      Coordination Chemistry: electron count, geometry, oxidation state, orbital interactions, types of ligands, binding modes, cis/trans and fac/mer isomers.

2)      Symmetry elements and point groups.

3)      Basic concepts on spectroscopy: NMR, Raman, IR, UV/Vis, XANES, EXAFS, neutron and X-ray diffraction

The more challenging group of questions include topics on:

1)      IR spectroscopy: fundamental vibrational modes, isotope effect

2)      Difference between η2 molecular hydrogen complexes and dihydride complexes.

3)      NMR spectroscopy: couplings, signal splitting and broadening, chemical shift

 

A supplemental question set has been included, which covers how to determine the 6 fundamental modes for the W(H2) portion of the entire molecule. This would be an advaned exercise, and notes for the instructor are also included.

Attachment Size
Kubas questions only.pdf 387.89 KB
Kubas questions only.docx 139.38 KB
Supplemental In-Class Exercise to Identify the 6 Fundamental Vibrations in M-H2 Complexes.docx 725.22 KB
Supplemental In-Class Exercise to Identify the 6 Fundamental Vibrations in M-H2 Complexes.pdf 591.16 KB
Learning Goals

After completing this exercise…

-Students will be able to recognize research that is important to the field

-Students will be able to assign oxidation state, coordination number, ligand characteristics, and 18-electron rule count for a metal complex

-Students will be able to consider various spectroscopic methods to studying complexes and reactions and what information can be obtained from them.

-Students will recognize the difference between X-ray diffraction and neutron diffraction

-Students will demonstrate the interactions between metals and ligands using frontier orbitals.

-Students will be able to assign point groups and use group theory to determine the number of IR and Raman-active vibrations for a molecule

Related activities
Otterbein Symmetry In-Class Activity/Take home activity
Good resource for Teaching IR with Symmetry Elements
Kecking over Electron Counting Formalisms? An In-Class Exercise in Counting Electrons for Ru Complexes with Proton-Responsive Ligands in the CBC and Ionic Methods
Activating H<sub>2</sub>: Mechanisms for Catalytic Hydrogenation and Hydroborylation
Vibrational Modes and IR Spectra using Character Tables
Implementation Notes

Give students a copy of the paper and discussion questions ahead of time.

 
Modifiy the questions based on the level of students that are in your class and what material you wish to focus on. 
 
Another idea would be to give groups of students just some of the questions, have them answer them and then present the answers to the class.  
 
Use the visualizations provided by Marion Cass (see web resources) to help inform the discussion with your students. 
Time Required
Entire class period
Web Resources
Marion's visualization site.
Kubas JACS paper
Evaluation
Evaluation Methods

Students will be evaluated with in-class participation and ability to work through the questions. 

Creative Commons License
Attribution, Non-Commercial, Share Alike CC BY-NC-SA