Oxidative Addition of Mel to Rhodium The Rate-limiting Step

Oxidative Addition of Mel to Rhodium - The Rate-limiting Step 

In summary, in order to accelerate the rate of Mel-oxidative addition (and consequently the rate of the overall process) electron-donating ligands need to be used. The IR stretch vibration of the CO coordinated to the metal can be indicative of the electron density on the rhodium center, but steric effects play a key role when relating it to reactivity versus Mel. 

---