Preparation and structures of 6- and 7-coordinate salen-type zirconium complexes and their catalytic properties for oligomerization of ethylene

摘要: Abstract A series of salen-type zirconium complexes the general formula LZrCl2 (L = N,N′-ethylenebis(salicylideneiminate), 3a; N,N′-ethylenebis(3,5-di-tert-butylsalicylideneiminate), 3b; N,N′-ethylenebis(5-methoxysalicylideneiminate), 3c; N,N′-ethylenebis(5-chlorosalicylideneiminate), 3d; N,N′-ethylenebis(5-nitrosalicylideneiminate), 3e; N,N′-o-phenylenebis(salicylideneiminate), 4a; N,N′-o-phenylenebis(3,5-di-tert-butylsalicylideneiminate), 4b; N,N′-o-phenylenebis(5-methoxysalicylideneiminate), 4c; N,N′-o-phenylenebis(5-chloro-salicylideneiminate), 4d) were prepared. The crystal structures 6- and 7-coordinate 4b [4b · OCMe2] determined by X-ray crystallography, which reveals that a complex possesses labile coordination site on Zr center with relatively stable framework dissociation O-donor molecules occur readily at this site. catalytic properties 3(a–e) 4(a–d) studied for ethylene oligomerization in combination Et2AlCl as co-catalyst. Complex 3c featuring methoxy-substituted salen ligand displayed higher activity than its analogous precursors having chloro nitro groups substituents. reactions gave C4–C10 olefins low-carbon linear α-olefins good selectivity.