Metallocenes early investigation

Based on an early process discovered by Natta in the 1950s, soluble transition metal catalysts like metallocenes were developed mainly in the 1950s as initiators for polyolefin syntheses. Others are still now under investigation, like the so-called LTM (for "late transition metal") catalysts. Metallocenes seem... 

Further ab initio investigations and electron-density analysis64 of silane coordination to early-metal metallocenes reveal that the agostic Si-H interaction in the Ti complex in Eq. (11.10) is quite strong despite the relatively short X-ray dSiH of... 

While the copolymerization of norbornene and ethylene by vanadium and titanium catalysts had been investigated in the 1970s, it was not until the invention of metallocene/MAO catalysts and their application to the homopolymerization of norbornene and other cycloolefins by Kaminsky et ai.8,15,19 that the use of early transition metal catalysts for the addition polymerization of norbornene drew new attention. Nevertheless, the industrial relevance of E/NB copolymers, and the nature of the homopolymers, described in the first reports as insoluble in organic solvents, crystalline, and extremely high melting, focused further investigations on copolymers rather than on norbornene homopolymers. 

These early results were obtained by investigating the ethylene polymerization behavior of zirconium and aluminum containing metallocene complexes shown as structures 1 and 2 in Figure 4.2 using trimethylalu-minum or triethylaluminum (TEAL) treated with water as activators [Ij. 

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