This in-class group activity provides several examples of varying difficulty for students to assign MLXZ classifications and electron counts to organometallic complexes. Though some of the problems are straightforward, some are really ambiguous, and the intent is for student groups to grapple with the issues raised by each one and present their findings to the class to spark further discussion.
Students are asked to find a coordination complex in the recent literature and analyze its structure. This homework or in-class activity is a great way for the instructor to crowd source the discovery of interesting new complexes to use as material in future exams.
In this exercise, students are introduced to Mercury, a program for visualizing and analyzing crystal structure data. Students are guided through opening the program for the first time and viewing a structure from the Teaching Subset, a selection of structures from the Cambridge Crystallographic Database (CSD). Activites include changing the representation of the complex, moving the structure around the window, accessing information about the structure, and measuring bond lengths and angles within the structure.
This is a two-week lab in which students synthesize and then characterize three Werner cobalt complexes using IR, UV/VIS and computer calculations using Spartan. Syntheses are based on procedures from:
Angelici, R. J. Synthesis and Technique in Inorganic Chemistry. University Science Books, 1996, pp 13-17.
Borer, L.L.; Erdman, H.W.; Norris, C.; Williams, J.; Worrell, J. Synthesis of trans-Tetraamminedichlorocobalt (III) chloride, Inorganic Syntheses, Vol 31, 1997, pp 270-271.
In this activity, students apply knowledge of the trans effect to the synthesis of planar Pt(II) complexes that contain cis-amine/ammine motifs. These complexes are of interest as both potential novel chemotherapeutic Pt(II) complexes and as intermediates for promising chemotherapeutic drugs such as satraplatin. The questions in this LO are based on recent research described in the paper “Improvements in the synthesis and understanding of the iodo-bridged intermediate en route to the Pt(IV) prodrug satraplatin,” by Timothy C. Johnstone and Stephen C.
I used this paper to illustrate several course concepts related to materials structure (crystal lattice structure, coordination number, crystal field theory and orbital splitting, symmetry, electronic spectra, allowed and forbidden transitions). This activity was paired with a laboratory experiment (see related VIPEr objects) in which students synthesized Prussian Blue, and gave students a really in-depth look at what was going on when they mixed those solutions together.
In this activity, the provided d orbital splitting patterns need to be matched with ligand geometries. Students are provided with the d orbital splitting diagrams for 6 ligand geometries (octahedral, trigonal bipyramidal, square pyramidal, tetrahedral, square planar, and linear). A web browser is used to view an animation (developed by Flick Coleman) which allows for the visualization of the relationship between the positions of the metal d orbitals and the ligands. Given this information, students should then be able to qualitatively rank the orbitals from highest to lowest energy.
I use this literature discussion in my second year inorganic class as a follow-up to a lab experiment where students synthesize Werner complexes and then (with much guidance) analyze their IR spectra using symmetry and group theory arguments. This paper provides an excellent example of how cobalt complexes are used in modern applications, and serves as a bridge to bioinorganic chemistry, which is a central feature later in the course.
Over the past several years, I've been doing this in-class exercise shortly after discussing mechanisms of ligand exchange. The exercise expands on the lecture material by having the students think about metal ions, rather than ligands, exchanging from a coordination complex. The students are encouraged to work in groups of 3-5 and actively discuss the material amongst themselves before we go over it as a class. I do not provide the students with the article ahead of time, so that they may come up with their own conclusions, as opposed to simply repeating those of the authors.