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