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. The idea is to have students think critically about experimental data (some of which is provided) and to have them consider how their predictions from group theory match up with historical conclusions drawn by the original researchers.
A student should be able to apply his or her knowledge of symmetry, group theory, and selection rules to answer each of the questions described in the activity. Furthermore, the students should develop an appreciation for the process of structure assignment based on spectroscopy and hopefully a little bit about the history of inorganic chemistry.
Having the original experimental papers handy is nice to quote the original authors' conclusions.