The O'Hare group has studied complexes of the permethylpentalene ligand, and recently reported the reaction of a zirconium complex of this ligand with CO₂ to form the carbamate. A series of three different complexes were prepared, each with slightly different products upon reaction with CO₂, illustrating subtle differences in reactivity based on either sterics or electronics. To further tangle the web, entropic and enthalpic considerations can also be considered. 

The discussion covers a 2021 publication by the Chirik group (Nature Chemistry, 2021, DOI: 10.1038/s41557-020-00614-w) which details the discovery of a new way to polymerize butadiene through iron-catalyzed [2+2] cycloadd

In this literature discussion, students are asked to explore the chemistry behind a eta-1 to eta-2 linkage photoisomer of sulfur dioxide bound to pentammine osmium. There are questions that tie to chemical structure and the nature of the two bonding modes of the ligand as well as an examination of the spectroscopic properties of the complex in the solid state. Two of the questions ask students to draw some conclusions based on their knowledge of periodic trends and the sigma donor ability of ligands.