A Frustrated Lewis Pair Based on a Cationic Aluminum Complex and Triphenylphosphine

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• 作者：Tom E. Stennett ; Jürgen Pahl ; Harmen S. Zijlstra ; Falk W. Seidel ; Sjoerd Harder
• 刊名：Organometallics
• 出版年：2016
• 出版时间：January 25, 2016
• 年：2016
• 卷：35
• 期：2
• 页码：207-217
• 全文大小：564K
• ISSN：1520-6041

文摘

The highly Lewis acidic, cationic aluminum species [DIPP-nacnacAlMe]⁺[B(C₆F₅)₄]^? (1, DIPP-nacnac = [HC{C(Me)N(2,6-ⁱPr₂C₆H₃)}₂]^?) has been shown to undergo reactions with a wide variety of small molecules, in both the presence and absence of an external weak phosphine base, PPh₃. Cycloaddition reactions of unsaturated C–C bonds across the aluminum diketiminate framework are reported, and the first structural confirmation of this type of cycloaddition product is presented. Addition of PPh₃ to 1 produces the cationic aluminum phosphine complex [DIPP-nacnacAl(Me)PPh₃]⁺[B(C₆F₅)₄]^?, which undergoes fluxional dissociation/coordination of the phosphine in solution. This weak Al–P interaction can be utilized in frustrated Lewis pair type reactions to activate alkenes, alkynes, CO₂, propylene oxide, and the C–Cl bonds of CH₂Cl₂. The CO₂ adduct [DIPP-nacnacAl(Me)OC(PPh₃)O]⁺[B(C₆F₅)₄]^? undergoes further stoichiometric reduction with Et₃SiH to produce an aluminum formate species.