11 Nov 2016

Molecular Hydrogen Complexes of Mo and W

Literature Discussion

Submitted by Kyle Grice, DePaul University

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.

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

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
Evaluation Methods: 

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

Creative Commons License: 
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