Another order of {HEAD ~ addition} involves initially contacting the electron donor with {TAIL ~ the co catalyst} 
Another order of { HEAD ~ addition } involves initially contacting the electron donor with { TAIL ~ the co catalyst }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL