Synthesis and Reactivity of Alkylzirconium Complexes Incorporating Asymmetrically Substituted ansa Ligands − X‐ray Crystal Structure of [Zr{Me2Si(η5‐C5Me4)(η5‐C5H3Me)}(CH2Ph)Cl]

Antiñolo, Antonío; Fernández‐Galán, Rafael; Gallego, Beatriz; Otero, Antonío; Prashar, Sanjiv; Rodrı́guez, Ana

doi:10.1002/ejic.200300150

Cited by 20 publications

(2 citation statements)

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“…Compounds 12 – 15 were characterized by spectroscopic methods, and complexes 12 and 13 were amenable to X‐ray diffraction studies. We have previously demonstrated that alkylation of silicon‐bridged ansa ‐zirconocenes is controlled by steric interactions between the alkyl ligand and the substituent on the cyclopentadienyl or similar group 31. The 1 H NMR spectra of these complexes show two unique signals at high field (between δ = –0.2 and –1.7 ppm) corresponding to the metal‐bonded methyl groups, thereby confirming dialkylation of the ansa ‐metallocene complexes.…”

Section: Resultsmentioning

confidence: 77%

Neutral Dimethylzirconocene Complexes as Initiators for the Ring‐Opening Polymerization of ϵ‐Caprolactone

et al. 2012

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The synthesis, structures, and ring‐opening polymerization (ROP) activity of new dimethyl‐ansa‐ and ‐non‐ansa‐zirconocene complexes are reported. The substituted indene precursors 1‐C9H7R [R = CH3 (1), CH2Ph (2) and C2H4(C4H7O2) (3)] were synthesised by treating RBr [R = CH2Ph and C2H4(C4H7O2)] or MeI with indenyllithium. Likewise, bridged indenyl/cyclopentadiene compounds [Me2Si(3‐C9H6R)(C5Me4H)] [R = H (4), CH3 (5), CH2Ph (6) and C2H4(C4H7O2) (7)] were obtained by treating the lithium salt of the appropriately substituted indene with ClSiMe2(C5Me4H). ansa‐Indenyl–cyclopentadienylmetallocenes [Zr{Me2Si(3‐η5‐C9H5R)(η5‐C5Me4)}Cl2] [R = H (8), CH3 (9), CH2Ph (10), C2H4(C4H7O2) (11)] were subsequently obtained by treating the dilithium salts of the corresponding ligands with ZrCl4 in toluene. The dimethyl derivatives [Zr{Me2Si(3‐η5‐C9H5R)(η5‐C5Me4)}Me2] [R = H (12), CH3 (13), CH2Ph (14), C2H4(C4H7O2) (15)] were prepared by treating the corresponding ansa‐zirconocene dichloride complex with MgMeBr. Dialkyl derivative [Zr{Me2Si{3‐η5‐C9H5(CH2Ph)}(η5‐C5Me4)}(CH2SiMe3)2] (16) was prepared by adding 2 equiv. of LiCH2SiMe3 to complex 10. Mixed indenyl/cyclopentadienylzirconocene complexes [Zr(η5‐C9H6R)(η5‐C5H5)Cl2] [R = H (17), C2H4(C4H7O2) (18)] were prepared by treating the lithium salt of the appropriately substituted indene with [Zr(η5‐C5H5)Cl3]. Likewise, dimethyl derivatives [Zr(η5‐C9H6R)(η5‐C5H5)Me2] [R = H (19), C2H4(C4H7O2) (20)] were prepared by treating the corresponding mixed indenyl/cyclopentadienyl dichloride complex with 2 equiv. of MgMeBr. The X‐ray crystal structures of 7, 12, and 13 were also established. Finally, comparative catalytic studies of zirconium complexes 12–16, 19 and 20 in ROP reactions of ϵ‐caprolactone are described.

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Section: Resultsmentioning

confidence: 77%

Neutral Dimethylzirconocene Complexes as Initiators for the Ring‐Opening Polymerization of ϵ‐Caprolactone

et al. 2012

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“…Similarly, MgCl(CH 2 SiMe 3 ) has been extensively used [27,28] to produce dialkyl derivatives of many metallocenes with free cyclopentadienyl ligands, whereas related ansa-metallocenes usually yield the corresponding monoalkyl compounds. [29] Consistently the dialkyl complex [Zr{(η 5 The enantiotopic face of the MBI ligand makes these dialkyl compounds, 2Ϫ4, asymmetric molecules with two nonequivalent alkyl groups. The 1 H NMR spectrum of 2 shows two singlets for the Zr-methyl groups, one shifted significantly highfield (δ ϭ Ϫ1.29) compared with the typical value (δ ϭ 0.09 ppm) observed for the other, which was in the range found for related methyl zirconocenes.…”

Section: Methodsmentioning

confidence: 96%

Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[e]indenyl ansa‐Zirconocene Complexes

et al. 2004

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Alkylation of ansa‐zirconocene [Zr{(η5‐C5H5)SiMe2(MBI)}Cl2] (MBI = η5‐2‐Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5‐C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono‐alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5‐C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI‐unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6‐xylyl isocyanide to give the iminoacyl compounds [Zr{(η5‐C5H5)SiMe2(MBI)}R{CR[η2‐N‐(2,6‐xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes were characterized by NMR spectroscopy and the X‐ray molecular structures of the dibenzyl and the imino‐benzyl compounds were determined. The catalytic activity for ethene polymerization and ethene/1‐hexene copolymerization of the dichloro zirconocenes [Zr{(η5‐C5H5)EMe2(MBI)}Cl2] (E = C, Si), activated with methylalumoxane (MAO), was measured. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Efficient One‐Pot Synthesis of N‐Containing Heterocycles by Multicomponent Coupling of Silicon‐Tethered Diynes, Nitriles, and Isocyanides through Intramolecular Cyclization of IminoacylZr Intermediates

Zhang

2010

Chemistry A European J

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An efficient multicomponent synthesis of 5-azaindoles and dihydropyrrolo[3,2-c]azepines was achieved by zirconocene-mediated coupling of silicon-tethered diynes, nitriles, and isocyanides. The synthesis, structures, and intramolecular cyclization of mono- and bis(iminoacyl)--Zr intermediates were investigated to elucidate the reaction process. Upon hydrolysis, the isolated mono(iminoacyl)--Zr intermediates underwent intramolecular cyclization to afford tetrasubstituted 5-azaindoles, whereas intramolecular cyclization of bis(iminoacyl)--Zr intermediates led to the formation of dihydropyrrolo[3,2-c]azepines. The structure of a bis(iminoacyl)--Zr intermediate, formed through insertion of two molecules of CyNC into the Zr--C bond, and structures of two dihydropyrrolo[3,2-c]azepines were characterized by single-crystal X-ray structural analysis.

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Synthesis and Reactivity of Alkylzirconium Complexes Incorporating Asymmetrically Substituted ansa Ligands − X‐ray Crystal Structure of [Zr{Me₂Si(η⁵‐C₅Me₄)(η⁵‐C₅H₃Me)}(CH₂Ph)Cl]

Cited by 20 publications

References 36 publications

Neutral Dimethylzirconocene Complexes as Initiators for the Ring‐Opening Polymerization of ϵ‐Caprolactone

Neutral Dimethylzirconocene Complexes as Initiators for the Ring‐Opening Polymerization of ϵ‐Caprolactone

Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[e]indenyl ansa‐Zirconocene Complexes

Efficient One‐Pot Synthesis of N‐Containing Heterocycles by Multicomponent Coupling of Silicon‐Tethered Diynes, Nitriles, and Isocyanides through Intramolecular Cyclization of IminoacylZr Intermediates

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