This morning before class I was picking on one of my students for having her organic chemistry textbook out on her desk. I believe I said something along the lines of 'how dare you contaminate my classroom with that!' She explained how she had an exam today and I let it drop. That is until later in the class when I was teaching about chelates. I had a sudden inspiration. I asked the student to pick up her organic book with one hand. I then warned her that I was going to smack the book. I did and she dropped it.

This in-class activity can be used to teach structural (or constitutional) isomers. This worksheet presumes that students have already had some experience with transition metal complexes such as determining metal oxidation state, recognizing the coordination sphere, and converting between formulas and structures.

Students are confronted with a number of new types of isomerism as they move from organic chemistry into inorganic chemistry. This can be confusing and students often have trouble visualizing structures and differentiating between isomers. In this exercise, students are asked to examine a number of different crystal structures from the Teaching Subset (distributed with Mercury version 3.10, early 2018) of the Cambridge Structural Database.

This exercise looks at the metal complexes of tropocoronand ligands, which were first studied by Nakanishi, Lippard, and coworkers in the 1980s. The size of the metal binding cavity in these macrocyclic ligands can be varied by changing the number of atoms in the linker chains between the aminotroponeimine rings, similar to crown ethers. These tetradentate ligands bind a number of +2 metal centers (Cd, Co, Cu, Ni, and Zn) and the geometry of the donor atoms around the metal center changes with the number of atoms in the linker chains.