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