Formation of a Titanium Complex with a Ti═CHAl2 Structural Unit from LTiMe3 and Trimethylaluminum
摘要:
The reaction of LTiCl3 (1) (L = HC(CMeN(2,6-iPr(2)C(6)H(3)))(2), nacnac) with MeLi center dot(Et2O)(0.14) in toluene afforded the stable Ti(IV) alkyl complex LTiMe3 (1). Reaction of 1 with 2 equiv of AlMe3 in toluene resulted in the formation of LTi(Me)=CH(Al2Me5) (2) in high yield. Compounds 1 and 2 were characterized by X-ray structural analysis, NMR, IR, mass spectrometry, and elemental analysis. The Ti-CH bond length (1.880(2) angstrom) of 2 is in the range of a short Ti-C bond. This was additionally supported by NMR and DFT calculations. Compound 2 polymerized ethylene without adding any cocatalyst, although activity is low; the best TOF value was 2.4 x 10(4) g(polymer)/mol catalyst . h . bar.