Using IR Frequencies to Compare Bond Strengths via Harmonic Oscillator Model
Inorganic chemists often use IR spectroscopy to evaluate bond order of ligands, and as a means of determining the electronic properties of metal fragments.
Inorganic chemists often use IR spectroscopy to evaluate bond order of ligands, and as a means of determining the electronic properties of metal fragments.
In honor of Professor Richard Andersen’s 75th birthday, a small group of IONiC leaders submitted a paper to a special issue of
In this literature assignment, students are asked to read an article from the primary literature on a binuclear manganese-peroxo complex that is similar to species proposed to be involved in photosynthetic water splitting and DNA biosynthesis. The assignment contains 25 questions that are intended to guide students through the article and help them extract important information about the work. The completed questions are then used as the basis for an in-class discussion of model complexes, which leads to a more advanced discussion on the topic.
When teaching my advanced bioinorganic chemistry course, I extensively incorporate structures from Protein Data Bank in both my assignments and classroom discussions and mini-lectures. I also have students access structures both in and out of class as they complete assignments.
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.
In the primary literature, goemetry indices are being used quite often to describe four- and five-coordinate structures adopted by transition metal complexes. This slide deck, which is longer than the intended 5 slides, describes the three common geometry indices (tau4, tau4', and tau5) and provides example calculations for structures that are freely available in the Teaching Subset of the Cambridge Structural Database. (Students can access these structures in Mercury, which is freely available from the CCDC, or via a web request form for which the link is provided below.)
Students in inorganic chemistry courses are often interested in the colors of transition metal complexes. This in-class activity serves an introduction to reactions of coordination complexes and pushes students to think about the relationship between the color of a complex cation and its structure. Students are provided with pictures of aqueous solutions of two chromium(III) salts [CrCl3*6 H2O and Cr(NO3)3*9 H2O] at two different times and are then asked to explain the changes observed in the solutions.