Synthesis of titanium trichloride complexes of 1,2,3-trisubstituted cyclopentadienyls and their use in styrene polymerization

The synthesis, characterization and styrene polymerization properties of titanium trichloride compounds (5, 1,3-dimethyl-2-n-butylcyclopentadienyl; 6, 1,3-dimethyl-2-t-butylcyclopentadienyl; 13, 1,3-diphenyl-2-n-butylcyclopentadienyl; 14, 1,3-dimethyl-2-phenylcyclopentadienyl; 15, 1,2,3-triphenylcyclopentadienyl) containing 1,2,3-trisubstituted cyclopentadienyl ligands are reported. Reactions of lithiated cyclopentadienide with Me3SiCl followed by addition of TiCl4 gave new titanium trichloride compounds 5 and 6, respectively, in reasonable yields, and reactions of cyclopentadiene with Ti(NMe2)4 followed by Me3SiCl or Me2SiCl2 gave new titanium trichloride compounds 13–15, respectively, in reasonable yields. Compound 14 has been characterized by single crystal X-ray diffraction studies: monoclinic space group P21/c; a=15.893(2), b=7.199(1), c=12.812(2) Å, β=108.394(7)°, Z=4 and V=1390.9(3) Å3. The catalytic behavior of the new titanium compounds in styrene polymerization has been studied in the presence of excess methylaluminoxane.