LIQUID-CRYSTALLINE TITANOCENE WITH CATALYTIC ACTIVITY FOR POLYMERIZATIONS OF ACETYLENE DERIVATIVES

Two kinds of liquid crystalline (LC) titanocenes have been synthesized with an aim to construct a new type of anisotropic polymerization fie ld. The titanocene derivatives were prepared by introducing LC groups into cyclopentadienyl ligands as substituents, (PCH506Cp)(2)TiCl2 (1) or coordinating them to titanium atom as ligands, Cp2Ti(PCH5060)(2)(2) . Observations of polarizing optical microscope and measurements of DS C indicated that 2 is the first titanium complex exhibiting a thermotr opic LC phase. We found that both the titanocene derivatives can polym erize phenylacetylenes to give poly(phenylacetylene)s with an aid of t riethylaluminium used as a cocatalyst. Molecular weights and polymeriz ation degrees of the polymers were comparable or superior to those by catalysts such as a titanocene dichloride [Cp2TiCl2] and a tetra-n-but oxytitanium [Ti(O-n-Bu)(4)]. The LC titanocene derivative (2) was also confirmed to have a high catalytic activity for acetylene polymerizat ion. These results should shed light on development of novel anisotrop ic reaction field available for syntheses of directly aligned conducti ng polymers.