Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines.
Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines.
复制标题
高路易斯酸性阳离子镁络合物与炔烃和膦的络合和多功能反应性。
作者：
Jürgen Pahl;Tom E. Stennett;Michel Volland;D. Guldi;S. Harder
[（BDI）Mg+ ][B（C6 F5）4 - ]（1; BDI=CH[C（CH 3）NDipp]2 ; Dipp= 2，6-二异丙基苯基）通过（BDI）MgnPr与[Ph 3 C+ ][B（C6 F5）4 - ]反应制备。加入3-己炔得到[（BDI）Mg+ Cl（EtClClClClClCl）][B（C6 F5）4 - ]。单晶X-射线分析，NMR研究，拉曼光谱，和DFT计算表明一个显着的镁-炔相互作用。添加末端炔PhC = CH或Me 3SiO 2 = CH导致通过BDI配体的炔去质子化，得到[（BDI-H）Mg+（C = CPh）]2·2 [B（C6 F5）4 - ]（2，70%）和[（BDI-H）Mg+（C = CSiMe 3）]2·2 [B（C6 F5）4 - ]（3，63%）。添加内炔PhC≡CPh或PhC≡CMe导致与BDI配体发生[4+2]环加成反应，得到{Mg+ C（Ph）=C（Ph）C[C（Me）=NDipp]2 }2·2 [B（C6 F5）4 - ]（4，53%）和{Mg+ C（Ph）=C（Me）C[C（Me）=NDipp]2 }2·2 [B（C6 F5）4 - ]（5，73%），其中Mg中心是N，N，C螯合物（BDI）Mg+阳离子可被视为具有刘易斯酸性位点（Mg）和刘易斯（或布朗斯特）碱性位点（BDI）的分子内受抑刘易斯对（FLP）。[（BDI）Mg+ ][B（C6 F5）4 - ]（1）与体积和给体强度不同的一系列膦反应生成[（BDI）Mg+ PtPPh 3][B（C6 F5）4 - ]（6）、[（BDI）Mg+ PtPPh 3][B（C6 F5）4 - ]（7）和[（BDI）Mg+ PtBu 3][B（C6 F5）4 - ]（8）。体积较大的膦PMes 3（Mes=均三甲苯基）没有显示出任何相互作用。[（BDI）Mg+ ][B（C6 F5）4 - ]和膦的组合并不导致3-己炔中的三键加成，但在筛选过程中发现阳离子镁络合物催化PhC CH 2CH与HPPh 2的氢膦化，初步提出了FLP型机理。
[(BDI)Mg+ ][B(C6 F5 )4 - ] (1; BDI=CH[C(CH3 )NDipp]2 ; Dipp=2,6-diisopropylphenyl) was prepared by reaction of (BDI)MgnPr with [Ph3 C+ ][B(C6 F5 )4 - ]. Addition of 3-hexyne gave [(BDI)Mg+ ⋅(EtC≡CEt)][B(C6 F5 )4 - ]. Single-crystal X-ray analysis, NMR investigations, Raman spectra, and DFT calculations indicate a significant Mg-alkyne interaction. Addition of the terminal alkynes PhC≡CH or Me3 SiC≡CH led to alkyne deprotonation by the BDI ligand to give [(BDI-H)Mg+ (C≡CPh)]2 ⋅2 [B(C6 F5 )4 - ] (2, 70 %) and [(BDI-H)Mg+ (C≡CSiMe3 )]2 ⋅2 [B(C6 F5 )4 - ] (3, 63 %). Addition of internal alkynes PhC≡CPh or PhC≡CMe led to [4+2] cycloadditions with the BDI ligand to give {Mg+ C(Ph)=C(Ph)C[C(Me)=NDipp]2 }2 ⋅ 2 [B(C6 F5 )4 - ] (4, 53 %) and {Mg+ C(Ph)=C(Me)C[C(Me)=NDipp]2 }2 ⋅2 [B(C6 F5 )4 - ] (5, 73 %), in which the Mg center is N,N,C-chelated. The (BDI)Mg+ cation can be viewed as an intramolecular frustrated Lewis pair (FLP) with a Lewis acidic site (Mg) and a Lewis (or Brønsted) basic site (BDI). Reaction of [(BDI)Mg+ ][B(C6 F5 )4 - ] (1) with a range of phosphines varying in bulk and donor strength generated [(BDI)Mg+ ⋅PPh3 ][B(C6 F5 )4 - ] (6), [(BDI)Mg+ ⋅PCy3 ][B(C6 F5 )4 - ] (7), and [(BDI)Mg+ ⋅ PtBu3 ][B(C6 F5 )4 - ] (8). The bulkier phosphine PMes3 (Mes=mesityl) did not show any interaction. Combinations of [(BDI)Mg+ ][B(C6 F5 )4 - ] and phosphines did not result in addition to the triple bond in 3-hexyne, but during the screening process it was discovered that the cationic magnesium complex catalyzes the hydrophosphination of PhC≡CH with HPPh2 , for which an FLP-type mechanism is tentatively proposed.
登录
查看更多内容
影响因子：
--
作者：
J. Langer;Irina Kosygin;R. Puchta;Jürgen Pahl;S. Harder
通讯作者：
J. Langer;Irina Kosygin;R. Puchta;Jürgen Pahl;S. Harder
影响因子：
4.6
作者：
Lawson, James R.;Melen, Rebecca L.
通讯作者：
Melen, Rebecca L.
基于阳离子铝配合物和三苯基膦的受阻路易斯对
影响因子：
2.8
作者：
T. E. Stennett;J. Pahl;H. S. Zijlstra;F. W. Seidel;S. Harder
通讯作者：
S. Harder
影响因子：
4
作者：
Garcia, Lucia;Anker, Mathew D.;Hill, Michael S.
通讯作者：
Hill, Michael S.