Titanacalixarenes in Homogeneous Catalysis: Synthesis, Conformation and Catalytic Activity in Ethylene Polymerisation

Abstract

Abstract Variously substituted titanacalixarenes were synthesised and tested for their performance as catalysts in ethylene polymerisation: p ‐ tert ‐butylcalix[4]arene was derivatised to afford distal diether p ‐ tert ‐butylcalix[4]arenes L1 – L4 , distal dihydroxy‐depleted L5 , proximal dihydroxy‐depleted L6 , proximal diether p ‐ tert ‐butylcalix[4]arene L7 , proximal intrabridged disiloxane L8 and proximal monoether L9 . (Dichlorotitana)‐ p ‐ tert ‐butylcalix[4]arenes 1 – 8 and (monochlorotitana)‐ p ‐tertbutylcalix[4]arene 9 have been successfully synthesised by reacting L1 – L4 with TiCl 4 · 2THF or L5 – L9 with TiCl 4 . The structural conformation of complexes 1 – 9 in solution were determined by 1 H NMR, 13 C NMR, NOESY and COSY spectroscopic studies. Compounds 2 , 3 and 4 have been structurally characterised by single‐crystal X‐ray diffraction. Upon activation with methylaluminoxane, compounds 1 – 8 revealed low to moderate activities for the production of high‐density polyethylene (HDPE) to ultra‐high‐molecular‐weight polyethylene (UHMWPE). 6 / MAO gave the best activity at 770 kg PE (mol Ti) –1 h –1 .