Pahl J, Stennett T, Volland M, Guldi DM, Harder S (2019)
Publication Type: Journal article
Publication year: 2019
Book Volume: 25
Pages Range: 2025-2034
Journal Issue: 8
[(BDI)Mg+][B(C6F5)(4)(-)] (1; BDI=CH[C(CH3)NDipp](2); Dipp=2,6-diisopropylphenyl) was prepared by reaction of (BDI)MgnPr with [Ph3C+][B(C6F5)(4)(-)]. Addition of 3-hexyne gave [(BDI)Mg+(EtCCEt)][B(C6F5)(4)(-)]. Single-crystal X-ray analysis, NMR investigations, Raman spectra, and DFT calculations indicate a significant Mg-alkyne interaction. Addition of the terminal alkynes PhCCH or Me3SiCCH led to alkyne deprotonation by the BDI ligand to give [(BDI-H)Mg+(CCPh)](2)2[B(C6F5)(4)(-)] (2, 70%) and [(BDI-H)Mg+(CCSiMe3)](2)2[B(C6F5)(4)(-)] (3, 63%). Addition of internal alkynes PhCCPh or PhCCMe led to [4+2] cycloadditions with the BDI ligand to give {Mg+C(Ph)=C(Ph)C[C(Me)=NDipp](2)}(2) 2[B(C6F5)(4)(-)] (4, 53%) and {Mg+C(Ph)=C(Me)C[C(Me)=NDipp](2)}(2)2[B(C6F5)(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 BrOnsted) basic site (BDI). Reaction of [(BDI)Mg+][B(C6F5)(4)(-)] (1) with a range of phosphines varying in bulk and donor strength generated [(BDI)Mg+PPh3][B(C6F5)(4)(-)] (6), [(BDI)Mg+PCy3][B(C6F5)(4)(-)] (7), and [(BDI)Mg+ PtBu3][B(C6F5)(4)(-)] (8). The bulkier phosphine PMes(3) (Mes=mesityl) did not show any interaction. Combinations of [(BDI)Mg+][B(C6F5)(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 PhCCH with HPPh2, for which an FLP-type mechanism is tentatively proposed.
APA:
Pahl, J., Stennett, T., Volland, M., Guldi, D.M., & Harder, S. (2019). Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines. Chemistry - A European Journal, 25(8), 2025-2034. https://dx.doi.org/10.1002/chem.201804802
MLA:
Pahl, Jürgen, et al. "Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines." Chemistry - A European Journal 25.8 (2019): 2025-2034.
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