For years, I spent 2-3 days a semester working through Tanabe-Sugano diagrams, their development from terms, their evolution from Orgel diagrams, their analysis to give transition energies (the old ruler- trial and error analysis) and nephalauxetic parameters. Recently, colleagues in VIPEr convinced me that my time in class could be better spent, but I am not willing to completely give up on Tanabe-Sugano. For that reason, I have developed this exercise that boils the application of T-S diagrams down to an exercise in interpreting graphs (a skill which is sadly lacking in some of my students). It omits some of the analysis of the T-S diagram, but I think it gives adequate coverage to what is truly the most useful information to be gleaned from T-S diagrmams.
A student should be able to identify the appropriate T-S diagram to use for a particular metal complex. A student should be able to predict whether a complex will be high-spin or low-spin and relate this to a particular position on the T-S diagram (x-axis). A student should understand that electronic transitions will not affect the value of either DelO or B, therefore any transition should be represented by a vertical line. A student should be able to predict the spin allowed transitions for a transition metal complex based on the appropriate T-S diagram. Given the necessary information to determine an exact x value (DelO/B), a student should be able to predict the energy of a particular electronic transition. A student should be able to convert n energy in wavenumbers to a wavelength in nm.
It may be helpful to provide students with rulers / straight edges. Students will need calculators.
It is helpful to have available for students a complete set of T-S diagrams, either from your textbook or photocopied.