The synthesis, structure and ethene polymerization activity of octahedral heteroligated (salicylaldiminato)(b-enaminoketonato)titanium complexes: The X-ray crystal structure of {3-Bu t -2-(O)C 6 H 3 CHN(Ph)}{(Ph)NC(Me)C(H)C(Me)O}TiCl 2 Dale A. Pennington a , Ross W. Harrington b , William Clegg b , Manfred Bochmann a , Simon J. Lancaster a, * a Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK b School of Natural Sciences (Chemistry), University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK Received 19 January 2006; received in revised form 13 March 2006; accepted 14 March 2006 Available online 18 March 2006 Abstract Treatment of the mono(salicylaldiminato)titanium complexes {3-Bu t -2-(O)C 6 H 3 CHN(Ar)}TiCl 3 (THF) (Ar = C 6 H 5 , 2,4,6-Me 3 C 6 H 2 or C 6 F 5 ) with the potassium b-enaminoketonates (C 6 H 5 )NC(CH 3 )C(H)C(R)OK (R = CH 3 , CF 3 ) yielded the first examples of heteroligated (salicylaldiminato) (b-enaminoketonato)titanium dichloride complexes. The complex {3-Bu t -2-(O)C 6 H 3 CHN(C 6 H 5 )}{(C 6 H 5 )- NC(CH 3 )C(H)C(CH 3 )O}TiCl 2 was structurally characterized by X-ray diffraction and has an orientation with trans-O,O,cis-Cl,Cl, cis- N,N distorted octahedral geometry. These complexes polymerize ethene when activated with MAO; the highest productivity, 5650 kg PE (mol metal) 1 h 1 atm 1 , was afforded by {3-Bu t -2-(O)C 6 H 3 CHN(C 6 F 5 )}{(C 6 H 5 )NC(CH 3 )C(H)C(CF 3 )O}TiCl 2 at 60 °C. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Homogeneous catalysis; Catalysis; Octahedral; Heteroligated; Titanium; Salicylaldiminato; Ethene; Polymerization 1. Introduction The development and mechanistic investigation of 1- alkene polymerization catalysis has long enjoyed a promi- nent position in the field of organometallic homogeneous catalysis. Pioneering work in the 1980s established that the active species in homogeneous group 4 metallocene cat- alysts was a metal alkyl cation [1]. Since the implicit recog- nition that the essential pre-requisite of an active catalyst is a vacant coordination site cis to a metal alkyl, a great vari- ety of coordination complexes in combination with methyl- aluminoxane and other alkylating and cation-generating reagents have been studied as potential polymerization cat- alysts [2]. Octahedral group 4 metal complexes supported by two monoanionic bidentate ligands such as the bis(salicylal- diminato) (I, Chart 1) [3], bis(pyrrolylaldiminato) (II) [4] and bis(b-enaminoketonato) (III) [5] metal dichlorides are amongst the most successful of these new catalyst classes. Varying the electronic and steric properties of two identical ancillary ligands has proven effective in modifying important catalytic parameters, namely the productivity, comonomer incorporation and chain trans- fer rate. However, there is generally a trade-off such that, for example, whilst sterically hindered systems such as the ortho-tert-butyl substituted bis(salicylaldiminato)titanium complexes are extremely productive ethene homopolymer- 0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2006.03.026 * Corresponding author. Tel./fax: +44 1603 592009. E-mail address: S.Lancaster@uea.ac.uk (S.J. Lancaster). www.elsevier.com/locate/jorganchem Journal of Organometallic Chemistry 691 (2006) 3183–3188