Active species and mechanism steps for the ethylene and styrene copolymerization process using the constrained geometry catalysts. E and St stand for ethylene and styrene monomers, respectively.
Simplified and real models for the constrained geometry catalysts based on titanium atom (Ti-CGC).
Results for the ethylene and secondary styrene monomer insertion into the Ti–Me, Ti–E and Ti–St species for the CGC-simplified and CGC-real catalysts at BP86 level obtained by Yang et al. and by us. Enclosed between parentheses are the results corresponding to level. Energies, negative frequencies, and distances corresponding to transition structures are given in kcal/mol, , and angstroms, respectively. ( n.a., not appreciable; n.d., not determined).
Effect of the polarization functions on the ethylene and secondary styrene monomer insertion into the Ti–Me and Ti–St species for the CGC-simplified catalyst. Calculations were done at BP86 level using a basis set without (LANL2DZ) and with (DZVP) polarization functions. These energies can be compared with those obtained by Yang et al. shown in Table I. Energies are given in kcal/mol.
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