1‐Decene oligomerization by new complexes bearing diamine‐diphenolates ligands: Effect of ligand structure

Abstract

A series of new titanium (IV) complexes bearing tetradentate diamine‐diphenolates, homologous to [ONNO] salan type ligands: [Ti{2,2′‐(OC6H2–4,6‐tBu2)2NHC3H6NH}(Cl)2] (Cat1), [Ti{2,2′‐(OC6H2–4,6‐tBu2)2NHC4H8NH}(Cl)2] (Cat2), and [Ti{2,2′‐(OC6H2–4,6‐tBu2)2NHC6H4NH}(Cl)2] (Cat3) were synthesized and fully characterized by elemental analysis and NMR spectroscopy. All three synthesized catalysts, after activation with ([Ph3C][B(C6F5)4]) as a cocatalyst, exhibited high activities in 1‐decene oligomerization experiments. Gel permeation chromatography (GPC) analysis showed that molecular weight of the obtained oligomers had a close relationship with employed ligand structures, so that by increasing length of the aliphatic linkage between nitrogen donor atoms, PDI (Mw/Mn) shifted to the higher values. 1‐decene oligomers obtained by the Cat3 exhibited highest isotactic value (92% tacticity). Kinetic calculations allowed us to formulate the elementary reaction steps in oligomerization process of the 1‐decene. At the viscosity characterization, KV100 amounts of 2.9, 3.9, and 4.1 cSt were determined for synthesized oligomers with Cat1, Cat2, and Cat3, respectively. High catalyst activity, capability of producing PAOs with KV100 < 6, less toxicity and corrosiveness of the catalytic system (compared to commercialized process based on the hazardous BF3 catalyst), and simplicity of the preparation procedure are the merits of the new reported catalysts.

Fluxional bis(phenoxy-imine) Zr and Ti catalysts for polymerization

“…DFT calculations were carried out to describe the thermodynamics and the interconversion processes of the three isomers of the cationic catalysts, bearing a methyl group on the metal (either zirconium or titanium) [79]. For the interconversion, there are two symmetric pathways: A → B → C and A′ → B′ → C′.…”

Chelation enforcing a dual gold configuration in the catalytic hydroxyphenoxylation of alkynes

“…[59,60] However, it is possible to study how the entering alkyne coordinates to contribute to the opening of the digold species with the phenoxide linking both gold centers (Step A -B in Figure 1). Table 2 contains the contributions that are part of the interaction energy associated with the formation of the Au-C bond between the phenoxide bridge among both gold atoms and diphenylacetylene, taking into account that the two IPr ligands are bridged by an alkyl chain, [61] of 2-11 methylene units.…”

Effect of support hydrophobicity of halloysite‐based catalysts on the polyalphaolefin hydrofinishing performance

“…In the continuation of our research on Hal-based catalysts for hydrogenation reactions, [44][45][46][47] herein, and knowing that the presence of protic solvents and reagents is detrimental for this reaction, [48][49][50] we wish to report a combined computational and experimental study on the effect of the hydrophobicity of Hal on its performance for hydrofinishing of PAO.…”