The ethylene complex Cp2Zr(C2H4)(PMe3) (1) reacts with tri- and tetrafunctional H-acidic compounds under protonation of the ethylene ligand to form bridged trinuclear and tetranuclear ethyl complexes: trioles like glycerol, 2-(hydroxymethyl)-2-methyl-1,3-propanediole and phloroglucine afford [CP2(Et)ZrO]3R (R = CH2CHCH2, CH3C(CH2)3, 1,3,5-C6H3). The tetrafunctional citric acid and pentaerythritol form with 1 bridged tetranuclear ethyl complexes.
DOI:
10.1016/0022-328x(92)80133-i
作为产物:
描述:
1.1-bis-(η5-cyclopentadienyl)-3-n-octyl-1-zirconacyclopentane 、 三甲基膦 在
乙基溴化镁 作用下,
以
not given 为溶剂,
以>63的产率得到Cp2Zr(C2H4)(PMe3)
参考文献:
名称:
Takahashi, Tamotsu; Seki, Takashi; Nitto, Yu, Journal of the American Chemical Society, 1991, vol. 113, # 16, p. 6266 - 6268
Factors Affecting the Unusual Reactivity Order in the β-Hydrogen Abstraction of Dialkylzirconocenes
作者:Ei-ichi Negishi、Thinh Nguyen、John P. Maye、Daniele Choueiri、Noriyuki Suzuki、Tamotsu Takahashi
DOI:10.1246/cl.1992.2367
日期:1992.12
Competitive β-hydrogen abstraction of “mixed” dialkylzirconocenes and kinetic measurements of decomposition of methyl(alkyl)zirconocenes reveal unexpected relative reactivity of alkyl groups as β-hydrogen donors, such as s-Bu > t-Bu ≥ Et > n-Bu > i-Bu, which correlate well in most cases with the reactivity order of: β-methyl > β-methylene > β-methine. Some mechanistically crucial features of the reaction are also discussed.
Structural determination of the first zirconocene–olefin complex, i.e., Cp2Zr(PhCH=CHPh)(PMe3), by X-ray crystallography is presented. Zirconium–olefin complexes such as ethylene and butene complexes can be selectively prepared in high yields from dialkylzirconocenes. On treatment of Cp2Zr(CH3)(PhCH2CH2) with, PMe3 a styrene complex 5 was obtained in good yield.
Addition of PMe3 to zircona– and hafna–cyclopentane derivatives afforded the corresponding zirconocene– and hafnocene–ethylenecomplexes, respectively, by C–C bond fission, the latter being the first example of hafnocene–alkene complexes.