Overview of Ring‐Opening Metathesis Polymerizations (ROMP) and Acyclic Diene Metathesis (ADMET) Polymerizations with Selected Ruthenium and Molybdenum Complexes

Well-defined ruthenium and molybdenum complexes that perform ring-opening metathesis polymerizations (ROMP) and acyclic diene metathesis (ADMET) polymerizations have become increasingly popular. The 2005 Nobel Prize in Chemistry highlights the significance of metathesis reactions. A very large number of metathesis catalysts are known for areas such as cross-metathesis (CM), ring-closing metathesis (RCM), asymmetric ring-opening metathesis (AROM), and tandem CM/RCM reactions. Although many melathesis catalysts are known for such areas, this chapter focuses on the synthesis and application of certain homogeneous Grubbs and Schrock alkylidene complexes within the framework of ROMP and ADMET polymerizations. Many metathesis catalysts and initiators have the ability to polymerize a wide variety of cyclic and acyclic alkenes. During ROMP and ADMET polymerizations, the initiation, propagation, and termination steps proceed through the well-known Chauvin mechanism involving a metallocyclobutane intermediate. Several reports have detailed and elucidated termination, decomposition, and isomerization mechanisms that can occur during ROMP and ADMET polymerizations.