This is an in-class exercise developed based on a recent paper in Angewandte Chemie International Edition that reported a crystal structure of "six-coordinate" carbon. We normally think of carbon being four-coordinate at most, but this case has definitive evidence otherwise. However, we can use our inorganic chemistry knowledge to understand the structure and bonding of this molecule and rationalize its stability. Students do a pre-class exercise and then construct the MO of fhe molecule in class together. 

This in-class worksheet introduces students to the different ways we describe organometallic ligands – bonding, properties, spectroscopy, etc. – using carbon monoxide as an example. It is structured as an inquiry-based activity, where students work together in small groups but check in with the entire class at appropriate intervals. I plan to use this activity with my advanced inorganic students next year.

Students work in groups to derive the ligand-field diagram for a square-pyramidal vanadium(III) oxo complex using octahedral V(III) as a starting point. The activity helps students to correlate changes in orbital energies as a function of changing ligands and geometry as well as rationalizing why certain geometries can be particularly good (or bad) for particular complexes. The activity also helps students see why oxo complexes of early metals are frequently best described as triple bonds.