Dynamic and Polymerization Behavior of Tetrabenzofluorenyl Titanium Complexes

6 DYNAMIC AND POLYMERIZATION BEHAVIOR OF TETRABENZOFLUORENYL TITANIUM COMPLEXES 

NMR spectroscopy reveals that in solution, both isomers rapidly interconvert as instead of a twofold signal set, which would be indicative of two isomers, only half the signal set can be observed at ambient temperature. Thus, temperature-dependent NMR experiments were conducted in order to determine the energetic barrier for interconversion of both isomers (Rg. 6.19). 

Run No. Catalyst Polymerization Time (min) Activity Melting Point (°C) 

The efficient syntheses of IVa allows an effective access to the organometallic chemistry of the Tbf moieties. Using the remarkable r -coordinated lithium salts y and VI, monosubstituted titanium(IV) alkoxides and aryloxides become available. The Tbf moiety is coordinated as a sterically demanding Cp derivative in an ii fashion to the titanium centers. The formal benzannula-tion of the fluorenyl system, as present in the Tbf titanium complexes, leads to large mono Cp complexes of high thermal stability compared to ii -fluorenyl titanium derivatives. Due to its heUcal twist, the T -coordinated Tbf ligands show Cl symmetry in the solid state but seem to interconverse in solution. Additionally, the titanium complexes were subjected to polymerization experiments of styrene to some extent. 

Janiak, C, Schumann, H. Bulky or supracyclopentadienyl derivatives in organo-metalUc chemistry. Adv. Organomet. Chem.,33,291-393 (1991). 

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