A novel transformation of a zirconium imido compound and the development of a new class of N-3 donor heteroscorpionate ligand

Reaction of the dimeric zirconium imido compound [Zr-2(mu-NAr)(2)Cl-4(THF)(4)] with tris(3,5-dimethylpyrazolyl)methyl silane very selectively gave [Zr{(Me(2)pz)(2)Si(Me)NAr}Cl-3] (1), a highly active pre-catalyst for ethylene polymerisation; a more general and versatile route to N-3 donor heteroscorpionate compounds was achieved via the protio ligand (Me(2)pz)(2)CHSi(Me)(2)N(H)Pr-i for which neutral and cationic organometallic Group 3 and 4 derivatives are reported (Ar = 2,6-(C6H3Pr2)-Pr-i).