ABSTRACT
Theoretical studies of the structure and properties of the active sites (AS) have begun immediately after discovery of the Ziegler -Natta catalysts [1, 2]. The important fact that the same element used as a transition metal may produce different polymerization products was comprehensively studied by theorists. For example, if isoprene is polymerized in the presence of TiC4-AlR3 catalyst, a polymer with predominant content of 1 ,4-cis-units is synthesized; in the case of TiCI4-MgR2 catalyst a polymer containing 80 - 99% of 1,4-trans-units is produced. Finally, isoprene polymerization on Ti(OR)3-AlR3 type catalytic system produces a polymer containing 93% of 3,4-cis-units [3, 4].
