Monocyclopentadienyl Phenoxido–Amino and Phenoxido–Amido Titanium Complexes: Synthesis, Characterisation, and Reactivity of Asymmetric Metal Centre Derivatives

Abstract

Reduction of phenol-imine derivatives RЈN=CH(3,5-R 2 C 6 H 2 -2-OH) (R = tBu; RЈ = C 6 H 5 1a, p-MeC 6 H 4 1b, Cy 1c, tBu 1d, 2,6-Me 2 C 6 H 3 1e; R = H; RЈ = p-MeC 6 H 4 1f; Cy = cyclohexyl) with MBH 4 (M = Li, Na) or AlLiH 4 in ethyl ether or thf at room temperature affords the phenol-amine compounds RЈNHCH 2 (3,5-R 2 C 6 H 2 -2-OH) 2a-c and 2e,f. The N-R- [2,4-ditert-butyl]benzo-1-oxa-3-azine species (R = tBu 2d1, 2,6-Me 2 C 6 H 3 2e1) are obtained by Mannich reaction of 2,4-ditert-butylphenol with RNH 2 in refluxing methanol. Intermediate 2d1 is converted in ethanol at room temperature into N-tert-butyl [2-hydroxy-3,5-di-tert-butyl]benzylamine (2d), whereas 2e is not obtained from 2e1 by using this procedure. N-alkyl,N-tert-butyl[2-hydroxy-3,5-di-tert-butyl]benzylamine compounds tBuN(R)CH

Studies on the active species in olefin polymerisation generated from phenoxo-amido titanium “chiral-at-metal” compounds

“…As observed in the reactions with TiCpCl 3 [32], treatment of the phenol-amine compounds RHNeCH 2 -(3,5-tBu 2 C 6 H 2 -2-OH) ( Cl 2 ] (6) (Scheme 3). The formation of these compounds can be interpreted as a result of TieCl bond aminolysis and alcoholysis reactions.…”

“…These complexes are interesting from basic coordination chemistry perspectives because only a few derivatives of this type are known. Initial studies of their ethylene polymerisation performance under MAO-activation conditions have also been reported [32]. It is interesting to analyse how the greater bulkiness and electron donor capacity of the permethylated cyclopentadienyl ring causes lower acidity at the titanium centre and consequently influences the behaviour of the analogous derivatives.…”

“…Previously, we have reported the synthesis of a series of cyclopentadienyl titanium complexes containing chelating dialkoxo [26e28] and diamido [29,30] ligands and studied the nature of the catalytic species in the a-olefin polymerisation processes generated by the reaction of these complexes with aluminium and boron reagents as cocatalyst [31]. As a part of a broad research programme aimed at investigating the catalytic performance of compounds with these characteristics, combining a cyclopentadienyl group and a chelating ligand, we have also recently reported the synthesis and polymerisation studies of various phenoxo-amido group 4 metal complexes stabilised by an unsubstituted cyclopentadienyl ligand (h 5 -C 5 H 5 ) [32].…”

Titanium (IV) and Nickel (II) Catalysts Based on Anilinotropone Ligands

“…Historically, the development of highly active olefin polymerization catalysts has been a trigger for creating new polymers which impact on our daily lives in countless beneficial ways [1][2][3][4][5]. A recent instance is the development of group 4 metallocene catalysts that exhibit very high ethylene polymerization activities [2,3].…”

“…A recent instance is the development of group 4 metallocene catalysts that exhibit very high ethylene polymerization activities [2,3]. Based on the highly active group 4 metallocene catalysts, high performance linear low-density polyethylene (LLDPE), isotactic poly-(propylene) (iPP) and syndiotactic polystyrene (sPS) etc., have been developed [6].…”