A catalyst obtained by contacting a compound of {HEAD ~ a transition metal} of {TAIL ~ the group V} of the Periodic Table represented by formula : 
of
A catalyst obtained by contacting a compound of { HEAD ~ a transition metal } of { TAIL ~ the group V } of the Periodic Table represented by formula :
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH