Early transition metal complexes bearing a C-capped tris(phenolate) ligand incorporating a pendant imine arm: Synthesis, structure, and ethylene polymerization behavior

摘要

The ligand 3-(2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-(2,6-diisopropyl)phenylimine] ((LH3)-H-1) was reacted with MCl4 (M = Ti, Zr) or MCl5 (M = Nb, Ta) to give complexes of the type [MCl2((LH2)-H-1)(2)] (M = Ti (1); Zr (2)), [NbCl3((LH)-H-1)] (3), or [TaCl4((LH2)-H-1)] (4), respectively. Single crystal X-ray diffraction of 1-4 revealed common "iminium" species resulting in zwitterionic complexes. Reaction of [V(Np-tol)(On-Pr)(3)] with (LH3)-H-1 afforded [{(VNp-tol)((LH)-H-1)}(2)(mu-On-Pr)(2)] (5), and a second complex [(VO)(2)(mu-O)((LH)-H-3)(2)] (6) ((LH)-H-3 being derived from 3-[2,2'-methylenebis(4,6-di- tert-butylphenol)-5-tert-butylsalicylidene-p-tolylimine]). The condensation reaction between 3-[2,2'methylenebis(4,6-di-tert-butylphenol)-5-tert-butyl-2-hydroxybenzaldehyde] ((LH3)-H-0) and o-phenylenediamine (1, 2-diaminobenzene) afforded two products: a pseudo-16-membered hydrogen bonded macrocyclic structure (1,2-bis-3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-benzyldiimine]) ((LH6)-H-5), or the benzimidazolyl bearing ligand ((LH3)-H-6). The reaction of (LH6)-H-5 or (LH3)-H-6 with [VO(Or-Pr)(3)] under varying conditions produced the complexes [(VO)((LH4)-H-5)] (7), [(VO)(2)((LH)-H-5)] (8), or [VO((LH2)-H-6)(2)] (9). LOH3 was reacted with a number of anilines to give the proligands (3-[2,2'-methylenebis(4,6-di-teit-butylphenol)-5-tert-butylsalicylidene-R-imine]), where R = NC6H5 ((LH3)-H-2), NC6H4Me ((LH3)-H-3), and NC6H2-Me-3 ((LH3)-H-4). Reactions of these ligands with [VO(On-Pr)(3)] formed bischelating complexes of the form [(VO)(L2-4H2)(2)] (10, 11, and 12, respectively). The reaction of (LH3)-H-1 with trimethylaluminum led to a bisaluminum complex {(AlMe2)[AlMe(NCMe)]L-1} (13). The ability of complexes 1-12 to polymerize ethylene in the presence of an organoaluminum cocatalyst was investigated. Procatalysts 1 and 2 were found to produce negligible activities in the presence of dimethylaluminum chloride (DMAC) and the reactivator ethyltrichloroacetate (ETA), whereas 3 and 4 were found to be completely inactive for polymerization using a variety of different organoaluminum cocatalysts. Using the combination of DMAC and ETA, complexes 5-12 were found to be highly active catalysts; in all cases, the polymer formed was of high molecular weight linear polyethylene.