Migratory insertion
![CO Insertion reaction pathway for an octahedral complex](/Images/godic/202501/27/Insertion_reaction_for_an_octahedral_complex3913.png")
![Steps in alkene polymerization. Step i involves binding of the monomer to the metal and step ii involves the migratory insertion step. These steps, which alternate from one side of the metal center to the other, are repeated many times for each polymer chain. The box represents a vacant (or extremely labile) coordination site.](/Images/godic/202501/27/AlkeneInsMech'3914.png")
![Migratory insertion of an alkene into a metal hydride. The middle image depicts the transition state. Notice that the less substituted carbon becomes bonded to the metal, at least usually. The reverse reaction is called beta-hydride elimination.](/Images/godic/202501/27/Beta-hydrideElim&TS3914.png")
![](/Images/godic/202501/27/Cativa-process-catalytic-cycle3914.png")
A migratory insertion is a type of reaction in organometallic chemistry wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions, and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.: