Zirconocene dichloride complexes with a 1,2-naphthylidene bridge as catalysts for the polymerisation of ethylene and propylene

Alt, Helmut G.; Baker, Robert W.; Dakkak, Mahmoud; Foulkes, Michael A.; Schilling, Marc; Turner, Peter

doi:10.1016/j.jorganchem.2004.03.021

Cited by 15 publications

(2 citation statements)

References 47 publications

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“…Alt et al, for example, have shown that ansa-complexes in which the metals (such as zirconium and other transitionand main-group atoms) are chelated to constrained rings can lead to unique metal coordination environments with significant utility as catalysts for polymerization and other reactions. [36,37] For the Groups 6, 7, and 8 metals, the bonding motif depicted in Figure 1 is thermodynamically stable, with binding enthalpies and free energies (per sandwich substituent) comparable to those of the corresponding simple RMR' sandwich systems. A linear equation that we uncovered provides insights into the ansa effect [35] in the C 6 A C H T U N G T R E N N U N G (RMR') 3 complexes.…”

Section: Strain and Geometrical Localizationmentioning

confidence: 92%

Predicting the Relative Stability of Simple versus ansa‐Sandwich Systems Across Groups: Structure, Bonding, and (In)Stability in Tris(sandwich)benzene Complexes

Donald

Bober

2011

Chemistry A European J

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We examine theoretically the bonding and thermodynamic stability of a proposed class of tris(sandwich)benzene complexes with the general formula C6(RMR′)3. In these systems, a single central (benzene) ring is flanked by three distorted 18‐electron sandwich fragments with M = Groups 6, 7, or 8 metals, and R and R′ = Ph or cyclopentadienyl (Cp) substituents. Remarkably, the computed free energy changes for the binding of the metal atoms to the organic fragments in 1) the ansa‐(C6(RMR′)3) complexes and 2) the simple (RMR′) sandwich complexes—for all the Groups 6, 7, and 8 metals—conform to the linear relationship: [ΔGbind(C6(RMR′)3)]/3 = ${\beta {{\Delta G\hfill \atop 1\hfill}}}$[ΔGbind(RMR′)]+${\beta {{\Delta G\hfill \atop 2\hfill}}}$ (R=0.989). The bonding and relative stabilities of these unusual tris(sandwich) and simple sandwich complexes are assessed at the B3PW91 level of theory employing small‐core relativistic MDF pseudopotentials and the corresponding basis sets for all the metals. The possible existence of strain‐induced bond localization (the so‐called Mills–Nixon effect) in the C6(RMR′)3 complexes and the aromaticity at the central benzene ring in C6(RMR′)3 are investigated. Despite the strain on the central ring, no bond fixation is observed. The tris(sandwich) complexes of Groups 6, 7, and 8 are all thermodynamically stable, relative to the free M atoms and organic fragments, with increasing stability as M gets heavier (going down the groups). The equation above also enables us to predict, by extrapolation, the (in)stabilities of the C6(RMR′)3 complexes of several other transition metals and helps us to better understand thermodynamic aspects of the ansa effect. Similar functions likely apply for other ansa variants of sandwich complexes.

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Section: Strain and Geometrical Localizationmentioning

confidence: 92%

Predicting the Relative Stability of Simple versus ansa‐Sandwich Systems Across Groups: Structure, Bonding, and (In)Stability in Tris(sandwich)benzene Complexes

Donald

Bober

2011

Chemistry A European J

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“…2-methyl-3-phenylindene 11 from methyl benzoate ( Fig. 5)], and Alt et al [12] installed a cyclopentadienyl group through reaction of the di-Grignard reagent derived from butadienemagnesium complex with a 2-naphthalenecarboxylate ester 12, followed by dehydration to the cyclopentadiene 13 ( Fig. 6).…”

Section: Preparation Of the Ligands 21 Formation Of Aryl-substitutementioning

confidence: 99%

Synthesis of Aryl- and Heteroaryl-Substituted Cyclopentadienes and Indenes and their Use in Transition Metal Chemistry

Enders¹,

Robert

2006

COC

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Self‐Immobilizing Catalysts for Olefin Polymerization

Alt

Görl

2008

Tailor‐Made Polymers

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Zirconocene dichloride complexes with a 1,2-naphthylidene bridge as catalysts for the polymerisation of ethylene and propylene

Cited by 15 publications

References 47 publications

Predicting the Relative Stability of Simple versus ansa‐Sandwich Systems Across Groups: Structure, Bonding, and (In)Stability in Tris(sandwich)benzene Complexes

Predicting the Relative Stability of Simple versus ansa‐Sandwich Systems Across Groups: Structure, Bonding, and (In)Stability in Tris(sandwich)benzene Complexes

Synthesis of Aryl- and Heteroaryl-Substituted Cyclopentadienes and Indenes and their Use in Transition Metal Chemistry

Self‐Immobilizing Catalysts for Olefin Polymerization

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