Titanium complexes bearing anionic [N,O -] bidentate salicylaldiminato ligands were synthesized with excellent yields via one-or two-step processes. The common feature of these catalyst precursors is the presence of aliphatic substituents (adamantyl, benzyl, (CH 2 ) 2 Ph, (CH 2 ) 3 Ph, and i-Pr) at the aldimino moieties. X-ray structure analysis of the benzyl-substituted complex revealed a distorted octahedral geometry, wherein nitrogen and chlorine atoms form the basal plane while the oxygen atoms of the phenoxy moieties complete the coordination sphere of the Ti center by occupying the axial positions. However, according to dynamic 1 H NMR measurements, these complexes can possess different structural isomers in solution, even at room temperature. After MAO activation, the catalysts displayed a range of catalytic activities [3-1700 kg PE /(mol Ti ‚h‚bar)]. The complex with ethylphenyl substituents was the most active in the series. In general, the (CH 2 ) 2 Ph-and (CH 2 ) 3 Ph-substituted catalysts produce PE with unimodal molar mass distribution, while the benzyl-, adamantyl-, and isopropyl-substituted catalysts tend to produce high molar mass bimodal PE with low activity. Computational methods were used to interpret the polymerization results, particularly the catalytic activity.

A series of titanium complexes bearing two anionic [N, O–] bidentate salicylaldiminato ligands, namely bis[(N‐salicylidene)anilinato]titanium(IV) dichloride (1), bis[(N‐salicylidene)‐2,6‐dimethylanilinato]titanium(IV) dichloride (2), bis[(N‐salicylidene)‐2,6‐di‐i‐ propylanilinato]titanium(IV) dichloride (3), bis[(N‐salicylidene)‐(1‐naphthalenylimino)]titanium(IV) dichloride (4), bis[(N‐salicylidene)‐2,6‐difluoroanilinato]titanium(IV) dichloride (5), and bis[(N‐3‐fluorosalicylidene)‐2,6‐difluoroanilinato]titanium(IV) dichloride (6) have been synthesized with good yields by a two‐step procedure. The X‐ray structure analysis reveals that in complex 2, titanium has a distorted octahedral coordination sphere in which the oxygen atoms and the chloride ligands form the basal plane. Both the chloride and the phenoxy moieties have a cis orientation and the angle between the chloride ligands is 93.05°. The imine nitrogen atoms complete the octahedral coordination of the Ti center by occupying the axial positions. The newly synthesized (2 and 4–6) and already known complexes (1 and 3) were introduced in detailed ethene‐polymerization studies. The activities achieved were low to moderate depending on the size and nature of the imino substituents. The polyethenes (PEs) produced had high molar masses, and the modalities of the molecular weight distributions varyied with polymerization temperature. Based on the results of ab initio calculations and on the experimental data obtained, an explanation for uni‐ and bimodal polymerization behavior and the differences in catalytic activities are given. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

A highly efficient, catalytic open-air ring opening polymerization for cyclic esters is reported. Using titanium alkoxides, Ti(OiPr) 4 and Ti(OnBu) 4 , as catalysts reproducible ROPs even with high monomer/initiator ratios without protecting gas are feasible. † Electronic supplementary information (ESI) available: Experimental details of the polymerization process, analyzing methods and the locations where the experiments were carried out. See

New chiral bridged tetradentate (N 2 O 2 )Ti IV Cl 2 -type complexes bearing dimethylbiphenyl (1-Ti-3-Ti) and previously published binaphthyl-bridged (4-Ti) complex were synthesized with high yields. This was achieved by treating the corresponding Schiff-base ligand (H 2 L) precursors with Ti(NMe 2 ) 4 , followed by conversion of these diamido complexes to LTiCl 2 derivatives by the addition of excess of Me 3 -SiCl. A series of unbridged titanium complexes 5-Ti-8-Ti with similar substituents at the phenoxy group were studied and their polymerization properties, after methylalumin-