Neodymium chloride isopropanol complex (NdCl3·3iPrOH) activated by modified methylaluminoxane (MMAO) was examined in isoprene polymerization in hexane

with regards to Nd compounds

aluminum (Al) compounds

[Al]/[Nd] ratio

polymerization temperature and time. NdCl3·3iPrOH exhibited high activity producing polymers featuring high cis-1

4 stereospecificity ( 96%)

very high molecular weight (Mn 1.0×106) and fairly narrow molecular weight distribution (MWD

Mw/Mn 2.0) simultaneously. In comparison

neodymium isopropoxide also showed high activity providing polymers with narrow MWD (Mw/Mn = 2.07)

but somewhat low cis-1

4 content (ca. 92%)

while neodymium chloride had no activity under present polymerization conditions. The Al compounds affected the polymer yield in the order of Al(i-Bu)3 MMAO Al(i-Bu)2H. MMAO as cocatalyst afforded polyisoprene with high Mn over 1.0×106

whereas as stronger chain transfer agent than MMAO

Al(i-Bu)3 and Al(i-Bu)2H yielded polymers with low Mn (1.0×105-8.0×105). NdCl3·3iPrOH/MMAO catalyst showed a fairly good catalytic activity even at relatively low [Al]/[Nd] ratio of 30

and the produced polymer remained high cis-1

4 content of 95.8% along with high Mn over 1.0×106 even at elevated temperatures up to 70οC. The polymerization rate is of the first order with respect to the concentration of isoprene. The mechanism of active species formation was discussed preliminarily.