Polymerization of 4-Methylpentene and Vinylcyclohexane by Amine Bis(phenolate) Titanium and Zirconium Complexes SHIMRIT GENDLER, 1 STANISLAV GROYSMAN, 1 ZEEV GOLDSCHMIDT, 2 MICHAEL SHUSTER, 3 MOSHE KOL 1 1 School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel 2 Department of Chemistry, Bar-Ilan University, Ramat Gan 52900, Israel 3 Research and Development Group, Carmel Olefins, Ltd., Haifa 1468, Israel Received 20 September 2005; accepted 27 October 2005 DOI: 10.1002/pola.21225 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: The polymerization of the substituted olefins 4-methylpentene and vinyl- cyclohexane by dibenzyl titanium and zirconium complexes of three amine bis(pheno- late) ligands is reported. The ligands featured a dimethylamino side-arm donor and either electron-withdrawing (Cl and Br) or methyl phenolate substituents. After acti- vation with B(C 6 F 5 ) 3 , the zirconium catalysts exhibited a higher activity than the titanium catalysts toward these bulky olefins. Very high weight-average molecular weight poly(4-methylpentene) was obtained with the zirconium catalysts. The zirco- nium catalysts were employed in 1-hexene polymerization, and their activity was found to be the highest ever reported for catalysts of the amine bis(phenolate) family. The catalysts featuring methyl phenolate substituents showed a higher activity toward these substituted olefins than the electron-poor catalysts; this trend was oppo- site to their activity toward 1-hexene. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1136–1146, 2006 Keywords: atactic; living polymerization; Ziegler–Natta polymerization INTRODUCTION Homopolymers and copolymers that are derived from the polymerization of branched a-olefins may possess potential technological value. For example, amorphous poly(vinylcyclohexane) has a high glass-transition temperature (T g ), high light transmittance, low intrinsic birefringence, and low water absorption and is, therefore, ex- pected to be useful as an optical disc material. 1 Since the early days of the Ziegler–Natta era, numerous attempts have been made to polymer- ize sterically hindered branched a-olefins. Natta and coworkers reported, among others, the poly- merization and crystal structures of isotactic poly (vinylcyclohexane) 2 and of isotactic poly(4-meth- ylpentene) with conventional heterogeneous cata- lysts. 3 However, the polymerization activity was low, and in addition, the polymerization reaction was complicated by monomer isomerization. 4 Similarly, the homogeneous catalysts based on metallocene complexes 5 showed low catalytic activity in the polymerization of these a-olefins. 6 Atactic poly(vinylcyclohexane) was normally pro- duced in a two-step sequence, which consisted of the polymerization of styrene and subsequent hydrogenation of the formed polystyrene. 7 More recently, higher activities in the polymerization of Correspondence to: M. Kol (E-mail: moshekol@post.tau.ac.il) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 44, 1136–1146 (2006) V V C 2005 Wiley Periodicals, Inc. 1136