Stereoselective Access to New Half-Sandwich Complexes Containing an Isodicyclopentadienyl Ligand

Abstract

The stereoselective synthesis, characterization, and X-ray crystal structure of a new example of a half-sandwich zirconium complex containing a nonplanar cyclopentadienyl ligand are reported. Preliminary ethylene polymerization results reveal catalyst activity that is comparable with related complexes.

How to synthesize a constrained geometry catalyst (CGC) – A survey

“…Notably, the permethylated cyclopentadienyl fragment still remains as the most frequently used unit for most catalytic applications. Other fused ring systems such as isocyclopentadienyl-based CGCs [72], heterocycle fused indenyl derivatives [73] or sterically expanded fluorenyl CGC [74] with unprecedented incorporation rates in the copolymerization process have been reported as well.…”

A doubly bridged isodicyclopentadienyl zirconium complex: bis{N-(3,5-dimethylphenyl)-N-[(η5-isodicyclopentadien-2-yl)dimethylsilyl]amido-κN}zirconium(II) diethyl ether solvate

“…Unsubstituted Cp rings give ansa-Cp±amido complexes in very low yield, whereas reactions with substituted Cp rings are quite ef®cient. We have demonstrated previously that the classical halfsandwich synthetic strategy can be readily adapted to the preparation of isodicyclopentadienyl±amido±zirconium±dichloro complexes (Gentil et al, 2000) by reaction with solid zirconium tetrachloride. In this paper, we report the preparation and structure of the complex bis{N-(3,5-dimethylphenyl)-N-[( 5 -isodicyclopentadien-2-yl)dimethylsilyl]amido-N}zirconium(II) diethyl ether solvate, obtained by the use of high amido±dilithium salt concentrations relative to zirconium tetrachloride.…”

“…The solvents were dried and distilled prior to use. (3,5-Dimethylphenylamino)(isodicyclopentadienyl)dimethylsilane was prepared according to published methods, using chloro(isodicyclopentadienyl)dimethylsilane (Gentil et al, 2000) and solid lithium (3,5-dimethylphenyl)amine in diethyl ether. To a solution of (3,5-dimethylphenylamino)(isodicyclopentadienyl)dimethylsilane (3.04 mmol, 897 mg) in diethyl ether (15 ml) at 195 K was slowly added n-butyllithium (6.1 mmol, 3.8 ml of a 1.6 M solution in hexane).…”

“…The ZrÐN bond lengths of 2.143 (2) A Ê for N1 and 2.135 (2) A Ê for N2 are longer than the ZrÐN bond length of 2.086 (1) A Ê in the exo-isodiCpSiMe 2 N-t BuZr(CH 2 SiMe 3 ) 2 complex (Gentil et al, 2000), but are comparable with the ZrÐN bond lengths of 2.142 (2) and 2.143 (2) A Ê in ( 5 -C 5 H 4 -CHMe-NPh-N) 2 Zr (Kunz et al, 2002), and the values of 2.137 (2) and 2.127 (2) A Ê in [ 5 -C 5 H 4 -Si(Me) 2 -NPh-N] 2 Zr . The sums of the bond angles at the two N atoms are essentially 360 (viz.…”

ansa-[(tert-Butylamino)(isodicyclopentadienyl)dimethylsilane]Zr(NMe2)2prepared by an amine-elimination reaction

“…Alternatively, such complexes can be prepared by an amine-elimination reaction with excellent ef®ciency (Hughes et al, 1993;Herrmann & Morawietz, 1994;Carpenetti et al, 1996;Leung et al, 1999). We have previously demonstrated that thè constrained geometry' complex [isodiCpSiMe 2 N-tert-butyl]-ZrCl 2 , where isodiCpSiMe 2 N-tert-butyl is N-tert-butyl-N-{[(1,2,3,3a,7a-)-4,5,6,7-tetrahydro-4,7-methano-1H-inden-2-yl]dimethylsilyl}amido, can be synthesized by the classical metathesis route in 55% yield (Gentil et al, 2000). In this paper, we report the high-yield`one pot' formation of [isodiCpSiMe 2 N-tert-butyl]Zr(NMe 2 ) 2 , (I), and its X-ray structure.…”