Imidazolin-2-Iminato Titanium Complexes

Dana Shoken, Schulich Faculty Chemistry, Technion-Israel Institute of Technology, Haifa, Israel
Moris Eisen, Schulich Faculty Chemistry, Technion-Israel Institute of Technology, Haifa, Israel
Matthias Tamm, Institute of Inorganic and Analytical Chemistry, , Braunschweig University of Technology, Braunschweig, Germany

In recent years, many studies about organometallic complexes containing imidazolin-2-iminato type ligands were published. Most likely due the ability of these ligands to donate 2σ, 4π electrons to the metal center hence, can be regarded as monodentate analogues to the important cyclopentadienyl ligands, C₅R₅. In addition, they exhibit rich chemistry by reacting with various metals throughout the periodic table.¹

In our group, we have focused our attention in exploring the ability of Imidazolin-2-iminato group 4 complexes for the polymerization of α-olefins. We have found that, mono imidazolin-2-iminato titanium chloride pre-catalysts can be activated with very low ratios of methylaluminoxane for ethylene polymerization.² These results are indeed exciting as most of the known metal complexes require high ratios of this co-catalyst to achieve high catalytic activities. Encouraged by these results, and since several studies have shown that the combination of different ligands might afford complexes which exhibit remarkable abilities for the copolymerization of ethylene with higher olefins,³ we have decided to continue and explore this complexes by reacting the mono titanium complexes with phenoxide type ligands and test them for olefin polymerization and co-polymerizations.

Here we present the synthetic pathway for the imidazolin-2-iminato phenoxide titanium compounds and there polymerization studies.     

1. Tamm, M.; Wu, X, Coord. Chem. Rev. 2014 , 260 , 116.

2. Shoken, D.; Sharma, M.; Botoshansky, M.; Tamm, M.; Eisen, M, S, J. Am. Chem. Soc. 2013, 135, 12592. 

3. (a) Nomura, K.; Fukuda, H.; Apisuk, W.; Trambitas, A, B.; Kitiyanan, B.; Tamm, M, J. Mol. Catal. A: Chem. 2014, 363, 501. (b) Nomura, K.; Komatsu, T.; Imanishi, Y, Macromolecules. 2000, 33, 8122.