RESUMO
Reaction of the dimeric zirconium imido compound [Zr2(mu-NAr)2Cl4(THF)4] with tris(3,5-dimethylpyrazolyl)methyl silane very selectively gave [Zr{(Me2pz)2Si(Me)NAr}Cl3] (1), a highly active pre-catalyst for ethylene polymerisation; a more general and versatile route to N3 donor heteroscorpionate compounds was achieved via the protio ligand (Me2pz)2CHSi(Me)2N(H)iPr for which neutral and cationic organometallic Group 3 and 4 derivatives are reported (Ar = 2,6-C6H(3)iPr2).
Assuntos
Imidas/química , Compostos Organometálicos/síntese química , Zircônio/química , Catálise , Cristalografia por Raios X , Etilenos/síntese química , Etilenos/química , Ligantes , Modelos Moleculares , Estrutura Molecular , Compostos Organometálicos/química , Pirazóis/química , Silanos/química , EstereoisomerismoRESUMO
Ethylene polymerisation productivities of tris(pyrazolyl)methane-supported catalysts [Ti(NR){HC(Me2pz)3}Cl2] show a dramatically different dependence on the imido R-group compared to those of their TACN analogues, attributed to differences in fac-N3 donor topology; when treated with AliBu3, the zwitterionic tris(pyrazolyl)methide compound [Ti(N-2-C6H4tBu){C(Me2pz)3}Cl(THF)] also acts as a highly active, single site catalyst (TACN = 1,4,7-trimethyltriazacyclononane).
Assuntos
Compostos Aza/síntese química , Imidas/química , Compostos Organometálicos/síntese química , Pirazóis/síntese química , Titânio/química , Boratos/química , Catálise , Ligantes , Estrutura Molecular , Polímeros/químicaRESUMO
Reaction of [M(CH2SiMe3)3(THF)2] (M = Sc or Y) with the neutral fac-kappa3 N3 donor ligands (L) Me3[9]aneN3 or HC(Me2pz)3 gave the corresponding trialkyls [M(L)(CH2SiMe3)3]; activation of the scandium congeners with B(C6F5)3 in the presence of ethylene afforded highly active polymerisation catalysts (Me3[9]aneN3 = 1,4,7-trimethyltriazacyclononane).
RESUMO
Tris(pyrazolyl)methanes are the neutral analogues of the widely exploited and highly useful tris(pyrazolyl)hydroborates, yet by comparison with their boron based counterparts their chemistry is underdeveloped. Recent breakthroughs in the synthesis of ring-substituted tris(pyrazolyl)methanes offer the opportunity for the development of this useful and promising class of ligand. This review summarises the current state of the coordination and organometallic chemistry of tris(pyrazolyl)methanes and highlights areas in which development is likely to occur.