Synthesis of Zirconium(IV) Monocyclopentadienyl−Aryloxy Complexes and Their Use in Catalytic Ethylene Polymerization. X-ray Structure of (η⁵-C₅Me₅)Zr{2,6-OC₆H₃(CH₃)₂}₃

Abstract

The complex Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Cl 2 (Cp* ) η 5 -C 5 Me 5 ) (1) has been prepared by the reaction of the starting material Cp*ZrCl 3 and 1 equiv of the lithium salt of the phenol compound. The reactions of 1 and the appropriate Grignard reagents afford the alkyl derivatives Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Me 2 (2) and Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(Bz)(Cl) (3). This and other dimethyl derivatives, namely, Cp*Zr(2,6-OC 6 H 3 Me 2 )Me 2 (4), Cp*Zr(O-2-t Bu-6-MeC 6 H 3 )-Me 2 (5), and Cp*Zr(O-2-C 3 H 5 -6-MeC 6 H 3 )Me 2 (6), can be obtained by reaction of Cp*ZrMe 3 and the corresponding phenol. When an excess of the less bulky 2,6-Me 2 C 6 H 3 OH phenol was used, the completely substituted complex Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 (7) was obtained. The reactivity of Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Me 2 in the insertion process of isocyanide compounds was studied. In all cases, the corresponding η 2 -iminoacyl compounds, Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(η 2 -MeCdNR)(Me) [R ) Xy (8); n Bu (9), Cy (10), TMB ) 1,1,3,3-tetramethylbutyl (11)], were obtained. Similar reactivity was found for Cp*Zr(2,6-OC 6 H 3 t Bu 2 )(Bz)(Cl) and Cp*Zr(O-2-t -Bu-6-MeC 6 H 3 )Me 2 . The complexes were characterized by spectroscopic methods, and in some cases, variable-temperature 1 H NMR spectroscopy studies were carried out. In addition, the molecular structure of Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 has been determined by X-ray diffraction methods. Finally, complexes Cp*Zr(2,6-OC 6 H 3 t Bu 2 )Cl 2 and Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 were tested as ethylene polymerization catalysts in the presence of MAO as cocatalyst. While the former complex shows a high activity similar to that found for classical metallocene catalysts, the latter is much less active. The different activities found for these complexes can be explained in terms of the different activation processes.

Half-sandwich β-diketonato complexes of zirconium and their application as catalysts to ethylene polymerization

“…This indicates that 1 behaves as single-site catalyst, suggesting relatively rapid alkylation of 1 by MAO (or the Me 3 Al in MAO). The activities of complexes 3 and 4 are much higher than that observed for their analogous oxygen coordination Zr complex, Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 (>100 times) [38] . The shorter Zr-O distance (1.95 Å) in Cp*Zr(2,6-OC 6 H 3 Me 2 ) 3 , compared with the Zr-O distance (2.11-2.26 Å) in 3 and 4, indicated a strong interaction between the metal center and the surrounding oxygen atoms, which partly contributes to the low rate of alkylation by MAO and then the low activity for ethylene polymerization.…”

Phosphine-Thiophenolate Half-Titanocene Chlorides: Synthesis, Structure, and Their Application in Ethylene (Co-)Polymerization

“…The resultant complexes were identified by 1 H, 13 C and 31 P NMR spectra and elemental analysis. The 1 H NMR spectra of these complexes showed no complexity, and the integration of complexes confirms a 1:1 ratio of cyclopentadienyl to phosphine-thiophenolate ligand.…”

“…H, 13 C and 31 P NMR as well as elemental analyses. Structures for 2a-b were further confirmed by X-ray crystallography.…”

“…The typical 13 C NMR spectra of poly(ethylene-co-NBE)s with different NBE incorporations are illustrated in Figure 3. [44][45][46][47][48][49][50][51][52][53][54][55][56] Figure 3A showed that the microstructures of the COCs formed using 2a under low NBE concentration of 0.3 mol/L possessed alternating ethylene-NBE sequences and isolated NBE units.…”

Synthesis of novel zirconium complexes bearing mono‐Cp and tridentate Schiff base [ONO] ligands and their catalytic activities for olefin polymerization

“…At the high temperature a decrease in the activity is a common behavior for the metallocene system, and the optimal polymerization temperature for each system depends on the balance between the propagation rate and the thermal stability. 37,38 Table 3 indicates that this type complexes are high thermal stability catalysts and the Schiff base ligand seems to play an important role in stablizing the active species. A high catalytic activity at high polymerization temperature should be important, especially from the aspect of industrial applications, because performing a solution polymerization at high temperature improves the viscosity of the reaction mixture, leading to better mass transportation and temperature control.…”