Half‐Titanocence Anilide Complexes Cp′TiCl 2 [N(2,6‐R 1 2 C 6 H 3 )R 2 ]: Synthesis, Structures and Catalytic Properties for Ethylene Polymerization and Copolymerization with 1‐Hexene

Mixed amido-cyclopentadienyl group 4 metal complexes

Two different kinds of nitrogen ligands and two Cp ligands with different electronic and steric effects were employed in order to demonstrate variability of the group 4 metal coordination spheres.

Access to Ultra-High-Molecular Weight Poly(ethylene) and Activity Boost in the Presence of Cyclopentene With Group 4 Bis-Amido Complexes

Zr^IV complexes of the type [Me₂ Si{(NR)(6-{2-(diethylboryl)phenyl}pyridyl-2-yl-N)}ZrCl₂ ⋅thf] (R=tBu (4), adamantyl (7 a); thf=tetrahydrofuran), [Me₂ Si{(NAd)(6-{2-(diphenylboryl)phenyl}pyridyl-2-yl-N)}ZrCl₂ ] (Ad=adamantyl (7 b)), the nonbridged half-titanocene complexes of the type [(N-{6-(2-diethylborylphenyl)pyrid-2-yl}-NR)Cp'TiCl₂ ] (R=Me, Cp'=C₅ H₅ (12), Cp'=C₅ Me₅ (13)), and the titanium(IV)-based metallocene-type complex [bis{N-(6-{2-(diethylboryl)phenyl}pyrid-2-yl)NMe}TiCl₂ ] (14) have been synthesized. The structures of complexes 7 b, 12, and 13 were determined by single-crystal X-ray diffraction analysis. In solution, complex 4 slowly rearranges to [Me₂ Si{(N-tBu)(6-{2-(diethylboryl)phenyl}pyridyl-2-yl-N)}₂ Zr] (4 a), the structure of which was unambiguously confirmed by single-crystal X-ray crystallography. Similarly, reaction of HfCl₄ with Me₂ Si({RNLi}{6-[2-(diethylboryl)phenyl]pyridyl-2-ylNLi}) yielded the corresponding Hf^IV complexes [Me₂ Si{(NR)(6-{2-(diethylboryl)phenyl}pyridyl-2-ylN)}₂ Hf] (R=tBu (8) and Ad (9)). Upon activation of these complexes with methylalumoxane (MAO), complexes 4, 7 a, 7 b, and 12-14 showed activities up to 750 kg of polyethylene (PE)/mol_cat.  bar h in the homopolymerization of ethylene (E), producing mainly linear PE (high-density PE, HDPE) with molecular weights in the range of 1 800 000<M_n <4×10⁶  g mol^-1 . In the copolymerization of E with cyclopentene (CPE), the polymerization activities of complexes 4, 7 a, and 7 b can be enhanced by a factor of 140 up to 7500 kg PE/mol_cat.  bar h, which produced PE-co-poly(CPE) containing 3.5 mol % of CPE. This dramatic increase in polymerization activity for E in the presence of CPE can be attributed to an involvement of CPE in the polymerization process rather than to solvent polarity.

Synthesis, characterization, and catalytic properties of new half-sandwich zirconium(IV) complexes

A number of new half-sandwich zirconium(IV) complexes bearing N,N-dimethylaniline-amido ligands with the general formula Cp*ZrCl(2)[ortho-(RNCH(2))(Me(2)N)C(6)H(4)] [R = 2,6-Me(2)C(6)H(3) (1), 2,6-(i)Pr(2)C(6)H(3) (2), (i)Pr (3), (t)Bu (4)] were synthesized by the reaction of Cp*ZrCl(3) with the corresponding ortho-(Me(2)N)C(6)H(4)CH(2)NRLi. All new zirconium complexes were characterized by (1)H and (13)C NMR, elemental analyses and single crystal X-ray diffraction analysis. The molecular structural analysis reveals that the NMe(2) group does not coordinate to the zirconium atom in all cases. Complexes 1-4 all have a pseudo-tetrahedral coordination environment in their solid state structures and adopt a three-legged piano stool geometry for the zirconium atoms with the amide N atom and the two Cl atoms being the three legs and the Cp* ring being the seat. Variable-temperature (1)H NMR experiments for all complexes 1-4 were performed to investigate the possible intramolecular interaction between the N atom in the NMe(2) group and the central zirconium atom in solution. Upon activation with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), complexes 1-4 all exhibit moderate to good catalytic activity for ethylene polymerization and copolymerization with 1-hexene, producing linear polyethylene or poly(ethylene-co-1-hexene) with moderate molecular weight and reasonable 1-hexene incorporation.

Half-zirconocene anilide complexes: synthesis, characterization and catalytic properties for ethylene polymerization and copolymerization with 1-hexene

A number of half-zirconocene anilide complexes of the type Cp*ZrCl(2)[N(2,6-R(1)(2)C(6)H(3))R(2)] [R(1) = (i)Pr (1, 3), Me (2); R(2) = Me (1, 2), Bn (3)] and Cp*ZrCl[N(2,6-Me(2)C(6)H(3))Me](2) (4) (Cp* = pentamethylcyclopentadienyl) were synthesized from the reactions of Cp*ZrCl(3) with the lithium salts of the corresponding anilide in diethyl ether at room temperature. All new zirconium complexes were characterized by (1)H and (13)C NMR and elemental analysis. Molecular structures of complexes 1, 2 and 4 were determined by single crystal X-ray diffraction analysis. Upon activation with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), complexes 1-4 exhibit good catalytic activity for ethylene polymerization, and produce polyethylene with a moderate molecular weight. Among these zirconium complexes, complex 1 shows the highest catalytic activity while complex 4 shows the lowest catalytic activity for ethylene polymerization. Complexes 1-3 also exhibit moderate catalytic activity for copolymerization of ethylene with 1-hexene, and produce copolymers with relatively high molecular weight and reasonable 1-hexene incorporation. In addition, the activation procedure of these catalyst systems were studied by (1)H NMR spectroscopy.