Mechanism
The catalysts used in the ROMP reaction include a wide variety of metals and range from a simple RuCl3/alcohol mixture to Grubbs' catalyst
The ROMP reaction is catalyzed primarily through the formation of metal-carbene complexes as first reported by Nobel Prize winner Yves Chauvin and his colleague Jean-Louis Hérisson although a hydride mechanism has also been reported. The initiation of the carbene species occurs through numerous pathways; solvent interactions, substituent interactions, and co-catalysts all can contribute to the production of the reactive catalytic species .
The ROMP catalytic cycle requires a strained cyclic structure because the driving force of the reaction is relief of ring strain. After formation of the metal-carbene species, the carbene attacks the double bond in the ring structure forming a highly strained metallacyclobutane intermediate. The ring then opens giving the beginning of the polymer: a linear chain double bonded to the metal with a terminal double bond as well. The new carbene reacts with the double bond on the next monomer, thus propagating the reaction
Read more about this topic: Ring Opening Metathesis Polymerisation
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