Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis

Massimiliano Toto; Luigi Cavallo; Paolo Corradini; Gilberto Moscardi; Luigi Resconi; Gaetano Guerra

doi:10.1021/ma980238w

Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis

Massimiliano Toto, Luigi Cavallo, Paolo Corradini, Gilberto Moscardi, Luigi Resconi, Gaetano Guerra^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

60 Scopus citations

Abstract

A possible rationalization of the dependence of regiospecificity of propene polymerization for catalytic systems based on C₂-symmetric ansa-zirconocenes (and hafnocenes) on the π-ligand alkyl substitutions is presented. With this aim, models of preinsertion intermediates and transition states for primary and secondary monomer insertion reactions are compared through molecular mechanics analyses. The nonbonded energy contributions to the regioselectivity, as well as the enantioselectivities of regioregular and regioirregular insertion steps have been investigated. Nonbonded energy interactions are able to account for the increases of regiospecificity experimentally observed for zirconocene-based catalytic systems when the π-ligands are alkyl substituted in position 2 or 3 as well as the decrease of regiospecificity observed when the π-ligands are dimethyl substituted in positions 4 and 7.

Original language	English (US)
Pages (from-to)	3431-3438
Number of pages	8
Journal	Macromolecules
Volume	31
Issue number	11
DOIs	https://doi.org/10.1021/ma980238w
State	Published - Jun 2 1998
Externally published	Yes

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Inorganic Chemistry
Materials Chemistry

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title = "Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis",

abstract = "A possible rationalization of the dependence of regiospecificity of propene polymerization for catalytic systems based on C2-symmetric ansa-zirconocenes (and hafnocenes) on the π-ligand alkyl substitutions is presented. With this aim, models of preinsertion intermediates and transition states for primary and secondary monomer insertion reactions are compared through molecular mechanics analyses. The nonbonded energy contributions to the regioselectivity, as well as the enantioselectivities of regioregular and regioirregular insertion steps have been investigated. Nonbonded energy interactions are able to account for the increases of regiospecificity experimentally observed for zirconocene-based catalytic systems when the π-ligands are alkyl substituted in position 2 or 3 as well as the decrease of regiospecificity observed when the π-ligands are dimethyl substituted in positions 4 and 7.",

author = "Massimiliano Toto and Luigi Cavallo and Paolo Corradini and Gilberto Moscardi and Luigi Resconi and Gaetano Guerra",

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T1 - Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis

AU - Toto, Massimiliano

AU - Cavallo, Luigi

AU - Corradini, Paolo

AU - Moscardi, Gilberto

AU - Resconi, Luigi

AU - Guerra, Gaetano

PY - 1998/6/2

Y1 - 1998/6/2

N2 - A possible rationalization of the dependence of regiospecificity of propene polymerization for catalytic systems based on C2-symmetric ansa-zirconocenes (and hafnocenes) on the π-ligand alkyl substitutions is presented. With this aim, models of preinsertion intermediates and transition states for primary and secondary monomer insertion reactions are compared through molecular mechanics analyses. The nonbonded energy contributions to the regioselectivity, as well as the enantioselectivities of regioregular and regioirregular insertion steps have been investigated. Nonbonded energy interactions are able to account for the increases of regiospecificity experimentally observed for zirconocene-based catalytic systems when the π-ligands are alkyl substituted in position 2 or 3 as well as the decrease of regiospecificity observed when the π-ligands are dimethyl substituted in positions 4 and 7.

AB - A possible rationalization of the dependence of regiospecificity of propene polymerization for catalytic systems based on C2-symmetric ansa-zirconocenes (and hafnocenes) on the π-ligand alkyl substitutions is presented. With this aim, models of preinsertion intermediates and transition states for primary and secondary monomer insertion reactions are compared through molecular mechanics analyses. The nonbonded energy contributions to the regioselectivity, as well as the enantioselectivities of regioregular and regioirregular insertion steps have been investigated. Nonbonded energy interactions are able to account for the increases of regiospecificity experimentally observed for zirconocene-based catalytic systems when the π-ligands are alkyl substituted in position 2 or 3 as well as the decrease of regiospecificity observed when the π-ligands are dimethyl substituted in positions 4 and 7.

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Influence of π-ligand substitutions on the regiospecificity and stereospecificity in isospecific zirconocenes for propene polymerization. A molecular mechanics analysis

Abstract

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