This lecture covers the discovery of alkene complexes, the bonding model for alkene-metal interactions, the synthesis methods for alkene complexes, and the rationalization of nucleophilic attack in these complexes. It also discusses the Dewer-Chatt-Duncanson model, the 18 VE rule, and the influence of CR3 groups on the bonding. The lecture concludes with examples of alkene complex reactions, such as polymerization and B-elimination, and the breakdown of rules for nucleophilic attack predictions.