Evidence for α-Nitrogen Participation in the Internal C−H Activation Reaction at ((Dimethylamino)methyl)cyclopentadienyl-Derived Methylzirconocene Cations
Evidence for α-Nitrogen Participation in the Internal C−H Activation Reaction at ((Dimethylamino)methyl)cyclopentadienyl-Derived Methylzirconocene Cations
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DOI：
10.1021/om990216d
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发表时间：
1999-08
期刊：
影响因子：
2.8
通讯作者：
J. Pflug;Axel Bertuleit;G. Kehr;A. Fröhlich;G. Erker
中科院分区：
文献类型：
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作者：
J. Pflug;Axel Bertuleit;G. Kehr;A. Fröhlich;G. Erker
用甲基锂处理 6-(二甲基氨基)-6-甲基富烯 (1)，然后将所得 [C5H4−CMe2NMe2]Li 试剂与 CpZrCl3 反应，得到络合物 [(η5-C5H4−CMe2NMe2)CpZrCl2] (2)。用 2 摩尔当量的甲基锂对其进行处理，得到 [(η5-C5H4−CMe2NMe2)CpZr(CH3)2] (3)。配合物3通过甲基转移与B(C6F5)3反应。以这种方式产生的原位[Zr]+-CH3阳离子系统被证明在反应条件下不稳定并立即消除甲烷并形成4。在该反应过程中，N-CH3氢原子被夺取。通过添加 1 当量的烷基异氰化物 RN⋮C (R = CMe3, n-C4H9, -CMe2CH2CMe3) 来稳定络合物 4，得到相应的加合物 5。 [(η5:η2(C,N)-C5H4−CMe2N(CH2)CH3)CpZr(κC-C⋮N−CMe3)]+[CH3B(C6F5)3]- (5a) 通过 X 射线晶体结构分析进行表征。它表现出悬挂的甲醛亚胺部分与锆的 η2-配位 (d(Zr−N) = 2.318(7) A, d(Zr−C) = 2.272(7) A)。 (η...
Treatment of 6-(dimethylamino)-6-methylfulvene (1) with methyllithium followed by the reaction of the resulting [C5H4−CMe2NMe2]Li reagent with CpZrCl3 gave the complex [(η5-C5H4−CMe2NMe2)CpZrCl2] (2). Its treatment with 2 molar equiv of methyllithium furnished [(η5-C5H4−CMe2NMe2)CpZr(CH3)2] (3). Complex 3 reacted with B(C6F5)3 by methyl group transfer. The in situ [Zr]+−CH3 cation system generated in this manner proved to be unstable under the reaction conditions and instantaneously eliminated methane with formation of 4. In the course of this reaction a N−CH3 hydrogen atom was abstracted. Complex 4 was stabilized by the addition of 1 equiv of the alkyl isocyanide RN⋮C (R = CMe3, n-C4H9, −CMe2CH2CMe3) to yield the respective adducts 5. The complex [(η5:η2(C,N)-C5H4−CMe2N(CH2)CH3)CpZr(κC-C⋮N−CMe3)]+[CH3B(C6F5)3]- (5a) was characterized by an X-ray crystal structure analysis. It exhibits an η2-coordination of the pendant formaldiminium moiety to zirconium (d(Zr−N) = 2.318(7) A, d(Zr−C) = 2.272(7) A). The (η...