|
Inorganic Chemistry |
Experiment 3 |
Spring 2024 |
Molecular modeling: Using HyperChem to generate M.O. diagrams
You will need to bring a jump drive to store your plots.
This experiment will involve the use of the molecular modeling program HyperChem 8.0. The details of the calculations have been previously discussed in the Physical Chemistry course.
Using HyperChem, calculate the orbital energies for the following molecules:
a) CO - draw the molecule with the correct number of bonds. Do a molecular mechanics calculation using mm+. This is done by going to SETUP, and choose MOLECULAR MECHANICS. Once the method is chosen, go to COMPUTE and select GEOMETRY OPTIMIZATION. When the program is finished with the calculation, do a semi-empirical calculation using pm3. Again, go to SETUP and choose SEMI-EMPIRICAL. Select the method of calculation and do a geometry optimization as above. Calculate the orbitals and note the order and energies. This is done by going to COMPUTE and down to ORBITALS. Include this diagram in your report. Do these match the MO diagram drawn in class?
Print out the HOMO and the LUMO for CO.
b) Do the same procedure for N2 as done for CO (using mm+ for the molecular mechanics and pm3 for the semi-empirical calculation). Note the orbitals for N2 and compare to the MO diagram done in class. Compare the two (CO vs N2). Next do the molecular mechanics for N2 using the program same as before (for CO), but now do the semi-empirical calculations for N2 using the INDO method. Note and compare results with the pm3 calculations for N2. Include both MO diagrams for N2 in your report.
Print out the HOMO and the LUMO for N2. (both
calculations)
.
c) Calculate the orbital diagram for F2 doing molecular mechanics
with mm+ and semi-empirical with MNDO. Compare the results with the
expected MO diagram (from class). Include this diagram in your report.
Print out the HOMO and the LUMO for F2.
Write up
Each person in the group must submit a separate
report. The report must follow the guidelines on the Lab Report
page. The experimental section will outline the procedure used in
modeling the compounds. The results section should include the orbital energy
diagrams (4 total - one for CO, two for N2 and one for F2)
and HOMO and LUMO for the four calculations. Be sure to compare the shapes and
energies of the HOMO's for the four plots. See the plots for HF for comparison.
The discussion section should answer the questions below each part of the experiment.
The MO diagrams from the lecture notes must be included and computer drawn (I
suggest either paint or PowerPoint drawings). This lab will be
worth 20 points and is due by 5:00 pm Friday, March 8, 2024. No late reports will be accepted.