Synthesis, characterization, and reactivity of titanium(IV) complexes supported by proximally bridged p-tert-butylcalix[4]arene ligands

Treatment of dilithium or dipotassium salt of p-tert-butylcalix[4]arene wit h (BuPCl2)-Bu-t or PhPCl2 produced 1,2-alternate phosphorus-bridged p-tert- butylcalix[4]arene derivatives ((BuPC)-Bu-t)H-2 (1) and (PhPC)H-2 (2), resp ectively. An X-ray diffraction study of 2 showed that it exists in 1,2-alte rnate conformation. Reaction of 2 with sulfur gave (PhSPC)H-2 (3), which ex ists in cone conformation. Treatment of TiCl4 with 1-3 produced the corresp onding dichlorides L2TiCl2 [L-2 = 'BuPC (5); PhPC (6); and PhSPC (7)]. Reac tion of R2Mg . 2THF (R = Me or CH2Ph) with (DMSC)TiCl2 (8) yielded (DMSC)Ti Me2 (9) and (DMSC)Ti(CH2Ph)(2) (10), respectively. Cationic derivatives [(D MSC)Ti(NCCH3)Me-2]BAr4F (11) and [(DMSC)Ti(NCCH3) (CH2Ph)]BAr4F (12) were p repared from the respective reactions of 9 and 10 with [Ph3C]BAr4F [ArF = ( CF3)(2)C6H3] in the presence of CH3CN. Similarly, 9 and 10 reacted with [Ph 3C]OTf tone equivalent) to yield [(DMSC)Ti(OTf)Me-2] (13) and [(DMSC)Ti(OTf )(CH2Ph)] (14), respectively. NMR data showed that the more exposed exo-alk yl was abstracted. Complexes 5-10 and 14 showed modest ethylene polymerizat ion activities at 25 degrees C with 500 molar equivalents of methylalumoxan e (MAO) as cocatalyst. (C) 1999 Elsevier Science S.A. All rights reserved.