SYNTHESIS, CHARACTERIZATION, AND REACTIVITIES OF THE POLYSILOXANE-BRIDGED BINUCLEAR METALLOCENES TETRAMETHYLDISILOXANEDIYLBIS(CYCLOPENTADIENYLTITANIUM TRICHLORIDE) AND HEXAMETHYLTRISILOXANEDIYLBIS(CYCLOPENTADIENYLTITANIUM TRICHLORIDE)

摘要

The reaction of dithallium salts of tetramethyldisiloxanediylbis(cyclopentadienyl) 3, and hexamethyltrisiloxanediylbis(cyclopentadienyl), 4, with two equivalents of TiCl4 gives the title compounds tetramethyldisiloxanediylbis(cyclopentadienyltitanium trichloride), 5 and hexamethyltrisiloxanediylbis(cyclopentadienyltitanium trichloride), 6 respectively. The stoichiometric reaction of 5 and 6 with water results in the formation of new oxygen-bridged metallocenes [(TiCl2)(2)(mu(2)-O)-(eta(5)-C5H4)(2)-mu(2)-(SiMe(2))(2)O], 7, and [(TiCl2)(2)(mu(2)-O)- (eta(5)-C5H4)(2)-mu(2)-(SiMe(2))(3)O-2}] 8, In addition, further reaction of 7 and 8 with another one equivalent of water or the treatment of 5 and 6 with an excess amount of water gives rise to the formation of the metallocene compounds having Ti4O4 rings [(TiCl)(2)(mu(2)-O)-(eta(5)- C5H4)(2)-mu(2)-(SiMe(2))(2)O](2)(mu(2)-O)(2) 9, and [(TiCl)(2)( mu(2)-O)-(eta(5)-C5H4)(2)-mu(2)-(SiMe(2))(3)O-2](2)(mu(2)-O)(2), 10. All the new kinds of metallocenes prepared have been characterized by IR, NMR, mass spectrometry, or elemental analysis, Especially an investigation of the de values in H-1 NMR and a comparison between the theoretical and observed isotopic ratio in a mass spectra among the synthesized bridged compounds have been very conveniently utilized to study their structures, Polymerization experiments with the dinuclear complexes in the presence of methylaluminoxane as a cocatalyst indicate that the compounds 5 and 6 do exhibit catalytic activity for syndiotactic polymerization of styrene. [References: 20]