A new chromium(III)/p-tert-butylcalix[4]arene/alkylaluminum catalyst system for the preparation of low molecular weight polyethylene

Niobium‐ and Tantalum‐Based Ethylene Polymerisation Catalysts Bearing Methylene‐ or Dimethyleneoxa‐Bridged Calixarene Ligands

“…The IR spectrum of this complex contained strong bands in the 600-800 cm À1 region consistent with nA C H T U N G T R E N N U N G (Nb À O À Nb) vibrations of bridging oxo groups and a shoulder at 3150 cm À1 that suggested the presence of nA C H T U N G T R E N N U N G (O À H). An X-ray study of the crystals obtained from a saturated solution in acetonitrile at 0 8C shows the compound to be the acetonitrile solvate [{Nb 2 (3). Stoichiometrically, 3 is formed through the loss of ten molecules of HCl from four equivalents of [NbOCl 3 ].…”

“…[7] Abstract: Treatment of p-tert-butylcalix [6]areneH 6 (5)), respectively. Complex 1, as well as [{Nb 2 (6), Ta (7)). The behaviour of 1 to 7 (not 3), as well as the known complexes [{(MCl)p-tert-butylcalix [4]arene} 2 ] (M= Nb (8), Ta (9)) and [(MCl 2 )p-tert-butylcalix [4]arene-A C H T U N G T R E N N U N G (OMe)] (M = Nb (10), Ta (11)), as procatalysts for the polymerisation of ethylene has been investigated.…”

“…[2] However, recently we have found that vanadyl complexes bearing dimethyleneoxa-bridged (-CH 2 OCH 2 -) oxacalix [3]arenes form extremely active catalytic species upon interaction with dimethylaluminium chloride (DMAC) in the presence of the re-activator ethyl trichloroacetate (ETA). Under the same catalytic conditions, vanadyl complexes bearing methylene-bridged (-CH 2 -) calix [4]arenes proved to have far inferior activities, though still far better than those observed previously for calix [4]arene-based systems.…”

Ultrahigh‐Molecular‐Weight Polyethylene by Using a Titanium Calix[4]arene Complex with High Thermal Stability under Polymerization Conditions

“…[3][4][5] Calixarenes are macrocyclic molecules consisting of phenol units linked via methylene bridges at the ortho positions of the phenol rings. They have found many applications in molecular and supramolecular chemistry, but surprisingly few studies have focused on the use of well defined calixarene complexes in ethylene polymerization.…”

Ring a bell: Disubstituted calix[4]arene as ligand for transition metal chlorides

“…as receptors for organic and inorganic analytes [1][2][3][4]. Substitution reactions [5] at the hydrophobic upper rim and the hydroxyl groups of the lower rim lead to the development of multifunctional sensors [6], capsule systems [7] and even catalytic properties [8][9][10]. Recent applications include also channel-type architectures for ion exchange [11], building blocks in metal organic frameworks (MOFs) [12], ion extraction [13] and antimicrobial properties [14].…”