Indenyl‐Titanchloride: Ethen‐Polymerisation und Struktur‐Reaktivitäts‐Untersuchungen

Indenyl‐Titaniumchlorides: Ethene‐Polymerization and Structure‐Reactivity Studies The halfsandwich complexes [(η 5 ‐C 9 H 7 )TiCl 3 ] ( 3a ), [(η 5 ‐Me 3 Si‐1‐C 9 H 6 )TiCl 3 ] ( 3b ), [(η 5 ‐Me‐1‐C 9 H 6 )TiCl 3 ] ( 3c ), [(η 5 ‐Me 2 ‐4,7‐C 9 H 5 )TiCl 3 ] ( 3d ), [(η 5 ‐Me 3 Si‐2‐C 9 H 6 )TiCl 3 ] ( 3e ), [(η 5 ‐Me 2 –1,3‐C 9 H 5 )TiCl 3 ] ( 3f ), [(η 5 ‐(CH 2 ) 3 –5,6‐C 9 H 5 )TiCl 3 ] ( 4 ), and [(η 5 ‐(CH 2 ) 3 –1,7‐C 9 H 5 )TiCl 3 ] ( 5 ) are accessible by reacting the in position 1 or 3 Me 3 Si‐functionalized appropriate indenes with TiCl 4 . CG‐TiCl 2 compounds (CG = C onstraint G eometry) can be synthesized by the subsequent reaction of Br‐2‐C 9 H 7 ( 6a ), Br‐2‐Me 2 ‐1,3‐C 9 H 5 ( 6b ) and Br‐2‐(CH 2 ) 3 ‐5,6‐C 9 H 5 ( 6c ), respectively, with magnesium in presence of Me 2 SiCl 2 to give the respective Me 2 SiCl‐functionalized indenes which further react with an excess of H 2 N t Bu to afford t BuHN‐SiMe 2 ‐2‐C 9 H 7 ( 8a ), t BuHN‐2‐Me 2 ‐1,3‐C 9 H 5 ( 8b ) and t BuHN–2‐(CH 2 ) 3 ‐5,6‐C 9 H 5 ( 8c ). The latter species produce on their consecutive reaction with n BuLi, [TiCl 3 ·3Thf] and PbCl 2 the titanium CG‐complexes [(η 5 ‐SiMe 2 N t Bu‐2‐C 9 H 6 )TiCl 2 ] ( 9a ), [(η 5 ‐Me 2 ‐1,3‐SiMe 2 N t Bu‐2‐C 9 H 4 )TiCl 2 ] ( 9b ), and [(η 5 ‐Me 2 SiN t Bu‐2‐(CH 2 ) 3 ‐5,6‐C 9 H 4 )TiCl 2 ] ( 10 ). The same synthesis protocol allows the preparation of [(η 5 ‐Me 2 SiN t Bu‐1‐Me 3 Si‐2‐C 9 H 5 )TiCl 2 ] ( 12 ) a CG complex in which the Me 2 SiN t Bu unit is located in position 1. The polymerization of ethene by using 3 – 5 and 9 – 12 and MAO (MAO = methylaluminoxane) as cocatalyst is described to show if a strong activity correlation between 3 – 5 and 9 – 12 exists. In order to optimize the catalytic activity of 3 – 5 the electronic (cyclic voltammetry, UV‐Vis spectroscopy) and steric properties (Multiple Overlap Solid Angle) of these species were analyzed. Based on the obtained data, semi‐empirical structure‐activity models for 3 – 5 are proposed to obtain an optimized substituent pattern for the indenyl moiety. Substituents in position 1 or 4 of the appropriate indenyl π‐perimeters show a strong bathochromic (+M) and electro‐neutral to electro‐negativ effect (0/‐I).