Coordination chemistry of the new preorganized polyphenoxide ligand tetrakis(2 -hydroxyphenyl)ethene derivatives. Attempts to create surface-models for classic Ziegler -Natta olefin polymerization catalysts

The derivatization of the newly developed preorganized tetraphenol ligand tetrakis(2-hydroxyphenyl)ethene, the coordination chemistry of the derived ligand systems, and verification of their potential as polymerization catalysts are described in this thesis.;Ortho-propylated analogue tetrakis(2-hydroxy-3-propylphenyl)ethene and selectively alkylated E- and Z-bis(2-hydroxyphenyl)-bis(2-methoxyphenyl)ethenes were synthesized as modified ligands of the parent system, tetrakis(2-hydroxyphenyl)ethene. The ability of these ligands to serve as templates for constructing polymetallic coordination complexes, especially hetero-polymetallic species, was examined by using three metal elements, titanium(IV), magnesium(II) and aluminum(III), as potential models of classic heterogeneous Ziegler-Natta catalysts.;The ortho-propylation of the ligand system contributed to the reduced tendency for intermolecular aggregation. Various coordination patterns and chemical reactivity were observed in the polynuclear complexes and were quite specific to the metal and other ligand groups. "All-up" trinuclear structures were always observed for magnesium complexes. "Up/down" dinuclear structures, mostly geminal, were preferred for titanium complexes. Aluminum complexes showed various coordination patterns, from six-membered crown ring systems to symmetrical and unsymmetrical dinuclear structures, depending upon the degree of exposure to a coordination solvent and the different substituents on the aluminum atoms. Several hetero-polymetallic complexes were also developed, starting from a magnesium complex.;The E-dialkylated ligand exhibited an ability to form well-organized titanium and aluminum complexes. The titanium complexes were all mono-nuclear, while both mono- and dinuclear aluminum complexes were obtained. The latter, however, basically consisted of a core mononuclear structure appended to an alkylaluminum reagent through a dative interaction. Attempted synthesis for aluminum/titanium hetero-polynuclear complexes extended our understanding of the ligand's coordination tendency. The Z-dialkylated ligand, on the other hand, was found to be a poor template for the construction of discrete metal complexes.;The titanium complexes of these preorganized phenoxide ligands showed poor ethene polymerization activity. Meanwhile, when titanium precatalysts were prepared in situ from the corresponding magnesium complexes, high polymerization activity was observed. The active catalytic species must somehow involve magnesium in the newly formed titanium aryloxide. This "magnesium effect" was not specific to preorganized systems, but also true for simpler phenoxide systems. The preorganization of the designed ligand systems contributed to the narrower polydispersity of the product polyethene.