1. Early metal complexes are electrophilic. Rapid binding of alkene increases kp
2. Group 4 complexes are d0. Back-bonding from metal to alkene is weak
lowering the activation energy for insertion, kp not reduced.
3. For metallocenes kp >>> kt leads to every metallocene being catalytically active
So called single-site catalysis leads to low polydispersity if ki is > kp
Many monomers can be polymerised by metallocenes but they are very sensitive
to water (need lot of MAO) and are intolerant to some monomer polar functional