In this in-class activity, students will determine the formal oxidation state of transition metal complexes by performing bonding type analysis of ligand−metal bonds. This in-class project is intended for those with little background in inorganic chemistry and aims to provide simple methods to calculate the formal charge of transition metals through bond-type analysis. While there are more sophisticated models already available to assign transition metal oxidation states, such as the LXZ (CBC) model, this exercise is intended for students who are coordination chemistry novices.

Students are often presented with the finished MO correlation diagrams of molecules like bis benzene chromium or ferrocene in classes and in organometallic chemistry text books. This activity helps them match the ligand group orbitals of the two benzene rings with the metal valence orbitals. Their understanding and appreciation of such diagrams is significantly enhanced when they find out how only some matches have the appropriate symmetry requirements.

Students work in groups to identify relevant steps and intermediates in 3 catalytic cycles, all the while considering bonding (and electron counting) factors.  Following assignment of these steps and intermediate species, the students consider several questions related to catalysis more broadly, particularly the role of each reagent, how to speed up or slow down specific steps, and the importance of regiospecificity in certain steps.