Type Imine Ligand (imidazol - 2 - Yl) - Ch = N - (ch < Sub > 2 < / Sub >) N - Cp And Its Transition Metal Complexes Synthesis, Characterization And Activity Evaluation

Polyolefins are top important high-molecular compounds in industry, agriculture, daily life, and other fields. Technology of their production is based on transition metal catalysts including catalysis with organometallic compounds. Major domestic and foreign companies and institutions have invested into this area of research in order to develop the catalysts with high activity, high stability and low cost for olefin polymerization. As a class of novel catalysts for olefin polymerization, imine catalysts for olefin polymerization have recently come into a focus of current research. These novel catalysts can achieve the same molecular design as metallocene catalysts and have already demonstrated many advantages over the metallocene ones, for instance, due to their lower price. In imine catalysts catalytic systems for olefin polymerization, an imido-group adjacent to an iso-or heterocyclic aromatic moiety presents the most typical element of the catalyst design. As an aromatic ensemble, pyridine and pyrrole are the most popular ones.Our laboratory has been engaged in the study of imidazole-functionalized ligands constrained geometry complexes derived from them for many years. In this work, we attempted to develop a practical synthetic approach to ligands of general type (imidazol-2-yl)-CH=N-(CH2)n-Cp’ and to complexes of Ti, Zr, Fe, Co, Ni or Ru based on them (Cp’ denotes methylcyclopentadienyl,tert-butylcyclopentadienyl and fluorene-9-yl).At first, the synthesis of the imidazole side chain functionalized monocyclopentadienyl imine ligands including6a,6b and6c was carried out. These ligands were prepared by the following scheme. A related Cp’-salt was reacted with2-bromoethylamine hydrobromide at low temperature that after isolation afforded Cp’-(CH2)n-NH2(5a-c) or its hydrochloride dependently on the isolation conditions. Compounds5a-c were reacted with imidazole-2-carboxaldehyde that afforded the target products6a-c. The structure of5a-c and6a-c was confirmed by GC-MS method and by1H13C{1H} NMR spectroscopy. Complexes5a-c and6a-c are all new compounds.The second part of the work presents an attempt to utilize ligand6c as the model one in the synthesis of bi-and tridentate mononuclear transition metal complexes. This attempt was performed in four ways. The first one involves deprotonation of6c with n-butyllithium. This way prepared Li-salt7c was reacted with titanium, zirconium, iron or nickel chlorides with expected formation of complexes (8c1-c4). The second way involved reaction of6c directly with titanium or zirconium tetramides, that gave complexes (8c5-c7) are obtained. The third method included a reaction of titanium or zirconium tetrachloride with6c in presence of triethylamine in toluene, that gave related products8c8-c9. The fourth method included a reaction of transition metal chlorides with6c in methanol, that gave related products8c10-c17., The complex7c and8c8showed good results by1H13C{1H} NMR spectroscopy.Finally, we investigated the olefin polymerization activity of8c8. The ethylene polymerization activity is morderate (1×104g PE/(mol Ti·atm·h)) of8c8activated by MAO.The research in preparation of transition metal complexes derived from the ligands6a-c is currently in progress in our research team.