This in-class activity traces the many contributions leading to the correct assignment for the solid-state structure of triiron dodecacarbonyl, [Fe₃(CO)₁₂],  with the aim of reinforcing ideas about IR spectroscopy and group theory. I give this activity to my advanced inorganic chemistry class (graduate students and senior undergrads). The activity is loosely based on the paper: Desiderato, R., Jr.; Dobson, G. R. J. Chem. Educ. 1982, 59, 752-756 and incorporates questions about symmetry and group theory for metal carbonyls.

Students work individually, then compete in teams, to identify symmetry elements and operations present in a high-symmetry structure, such as an octahedron or tetrahedron (without showing the character table until the end of the activity).  Students often  visualize symmetry elements differently from one another.  Creating teams, allows them to work collaboratively, and the competition adds an incentive for finding the most elements.  Since some students are better at seeing some symmetry elements (and operations) than others, it allows for them to work in small groups to both teach and lea

The original description of the synthesis of [RuH(NO₃)(CO)₂(PPh₃)₂ appears in Inorg. Chem. (Critchlow, P. B.; Robinson, S. D. Inorg. Chem. 1978, 17, 1896). There are eight possible structures for this octahedral isomer (including two sets of enantiomers). Students are shown one of the structures and asked to draw the remaining seven. The authors analyze the spectroscopic data obtained for the compound in order to determine which isomer formed. Unfortunately, there was an error in the analysis.

Metal carbonyls are the most widely studied organometallic complexes.  This exercise uses Gaussian with the GaussView interface to investigate the role of the metal centers on backbonding to the CO ligand. Density Functional Theory (DFT) methods were used to evaluate two classic metal pentacarbonyls, namely Fe(CO)₅ and Ru(CO)₅.