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Students are often presented with the finished MO correlation diagrams of molecules like bis benzene chromium or ferrocene in classes and in organometallic chemistry text books. This activity helps them match the ligand group orbitals of the two benzene rings with the metal valence orbitals. Their understanding and appreciation of such diagrams is significantly enhanced when they find out how only some matches have the appropriate symmetry requirements.
| Attachment | Size |
|---|---|
| mix_and_match_2.pptx | 587.87 KB |
1. A student should gain better appreciation of the molecular orbitals formed by interacting orbitals on the benzene ring and the valence orbitals of the metal .
2. A student should understand the difference between sigma, pi and delta type interactions.
3. Help the student understand why only a few orbitals on the benzene ring and the valence orbitals of the metal can interact.
Print outs of the ligand group orbitals and the metal valence orbitals on as thin a paper as possible.
A pair of scissors.
Evaluation
To make evaluation possible, the students were given the full set of orbitals printed on three A4 size sheets and asked to match all of them.
Depending on the number of correct matches, the correct identification and correct shading, they were given points.
Alternatively, they were asked to do it at their leisure.
There is no direct evaluation of the student at the end of this exercise. But the bright smiles on their faces after they find a perfect match suggests that they understand it better than before!
I have used it in undergraduate classes with good success. The students enjoy this activity and at the same time gain a better understanding of orbital interactions.