This paper in Science reports the synthesis of decamethyldizincocene, a stable compound of Zn(I) with a zinc-zinc bond. The title compound and the starting material, bis(pentamethylcyclopentadienyl)zinc, offer a nice link to metallocene chemistry, electron counting, and different modes of binding of cyclopentadienyl rings as well as more advanced discussions of MO diagrams. More fundamental discussion could focus on the question of what constitutes the evidence for a chemical bond, in this case, the existence of a zinc-zinc bond.
Students are asked to read the paper and the accompanying Perspecitves article before class as well as answer the discussion questions. The questions serve as a useful starting point for class discussion. I also took this opportunity to introduce the MO diagram for ferrocene to illustrate the 18 electron rule.