SYNDIOSPECIFIC POLYMERIZATION OF STYRENE .3. CATALYST STRUCTURE

The active oxidation state of Ti in the cyclopentadienyltributoxyltitanium methylaluminoxane (CpTi(OBu)3/MAO) catalyst has been determined by electron paramagnetic resonance (EPR) and redox titration. The results, together with previously reported active species concentrations measured by radiolabeling techniques, showed that all the catalytic species are trivalent Ti. The syndiospecific species (78% Ti) is characterized by a sharp EPR resonance at g = 1.989 ((H)a = 7 G) which corresponds to a titanium(III) hydride. The nonspecific species (13% Ti) has a g value at 1.995.