CIS-ISOTACTIC 1,4-POLYPENTADIENE - NMR SOLUTION CHARACTERIZATION AND CRYSTAL-STRUCTURE OF POLYMERS PREPARED WITH NEODYMIUM-CATALYTIC SYSTEMS

The synthesis of cis-1,4-isotactic polypentadiene with Neodymium (Nd)- catalytic systems yields polymers of higher stereoregularity than prev iously available and made possible the determination of the crystal st ructure of this polydiene. The lattice is orthorhombic with a = 9.49, b = 6.07, and c (fiber axis) = 8.17 Angstrom; space group P2(1)2(1)2(1 ) implies the presence of two isochiral chains in the unit cell. The r efinement of the crystal structure also establishes the details of the structure confirming the (CS+TS-)(2) chain conformation originally pr oposed on the basis of the fiber repeat.