کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1322883 1499912 2013 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Stereocontrolled monoalkylation of mixed-ring complex CpCp′ZrCl2 (Cp′ = 1-neomenthyl-4,5,6,7-tetrahydroindenyl) by lithium, magnesium and aluminum alkyls
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Stereocontrolled monoalkylation of mixed-ring complex CpCp′ZrCl2 (Cp′ = 1-neomenthyl-4,5,6,7-tetrahydroindenyl) by lithium, magnesium and aluminum alkyls
چکیده انگلیسی

The monoalkylation of mixed-ring complex η5-cyclopentadienyl-η5-(1-neomenthyl-4,5,6,7-tetrahydroindenyl)zirconium dichloride (CpCp′ZrCl2) by lithium, magnesium and aluminum alkyls has been studied by the means of NMR spectroscopy. It is shown the reaction of CpCp′ZrCl2 with 1 eq. of RLi (R = Et, nBu) at −78 °C in toluene gives the chiral-at-zirconium complexes CpCp′ZrRCl with epimer ratio 12:1. The use of Grignard reagent (EtMgBr) reduces the epimer ratio to 3:1. The reaction of CpCp′ZrCl2 with AlEt3 in the same conditions yields two diastereomers of complex [CpCp′ZrEt(μ-Cl)·AlEt3] in a ratio 1.6:1, followed by five-membered bimetallic hydride complex [CpCp′Zr(μ-H)(CH2CH2AlEt2] with diastereomeric ratio 10:1.Cyclohexyl isocyanide (CyNC) insertion into the Zr-R bond of CpCp′ZrRCl provides the corresponding η2-iminoacyl complexes CpCp′ZrC(R) = N(Cy)(Cl) (R = Et, nBu), which were characterized by NMR, IR spectroscopy and mass-spectrometry (MALDI/TOF).

The monoalkylation of CpCp′ZrCl2 with Li, Mg and Al alkyls gives chiral-at-metal complexes CpCp′ZrRCl (R = Et, nBu). The diastereoselectivity of the reaction decreases in the series RLi > EtMgBr > AlEt3. Addition of CyCN to CpCp′ZrRCl provides η2-iminoacyl complexes СpCp′ZrC(R) = N(Cy)(Cl).Figure optionsDownload as PowerPoint slideHighlights
► Monoalkylation of CpCp′ZrCl2 by RLi (R = Et, nBu) or EtMgBr gives chiral-at-zirconium complexes CpCp′ZrRCl.
► Reaction of CpCp′ZrCl2 with AlEt3 yields diastereomeric complexes [CpCp′ZrEt(μ-Cl)·AlEt3] and [CpCp′Zr(μ-H)(CH2CH2AlEt2].
► Diastereoselectivity of monoalkylation decreases in the series RLi > EtMgBr > AlEt3.
► Addition of CyNC to CpCp′ZrRCl provides η2-iminoacyl complexes CpCp′ZrC(R) = N(Cy)(Cl) (R = Et, nBu).

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Organometallic Chemistry - Volume 726, 15 February 2013, Pages 37–45
نویسندگان
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