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Issue 12, 2017
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Metal-free pincer ligand chemistry polycationic phosphonium Lewis acids

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Abstract

Oxidation of 2,6-bis(diphenylphosphine)methyl pyridine with MeO3SCF3, yields the dication [2,6-(CH2PMePh2)2C5H3N][CF3SO3]22, while subsequent treatment with two equivalents of [K(THF)n][B(C6F5)4] (n = 1.3–1.5) afforded [2,6-(CH2PMePh2)2C5H3N][B(C6F5)4]23. Analogous treatment using XeF2 afforded 2,6-(CH2PF2Ph2)2C5H3N 4, while subsequent fluoride abstractions afford the corresponding [BF4], [CF3SO3] and [B(C6F5)4] salts, 5–7, respectively. Compound 4 reacts with an excess of MeO3SCF3 to give [2,6-(CH2PF2Ph2)2C5H3N(CH3)][CF3SO3] 8 while subsequent reaction with [Et3Si·2C7H8][B(C6F5)4] gave the related tricationic species, 9. The Lewis acidity of these di- and triphosphonium cations 3, 7 and 9 was examined and their utility as Lewis acid catalysts was assessed in the dimerization of 1,1-diphenylethylene, the hydrodefluorination of 1-fluoroadamantane, and the dehydrocoupling of phenol and silane.

Graphical abstract: Metal-free pincer ligand chemistry polycationic phosphonium Lewis acids

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Publication details

The article was received on 04 Feb 2017, accepted on 28 Feb 2017 and first published on 01 Mar 2017


Article type: Paper
DOI: 10.1039/C7DT00441A
Citation: Dalton Trans., 2017,46, 3921-3928
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    Metal-free pincer ligand chemistry polycationic phosphonium Lewis acids

    K. M. Szkop and D. W. Stephan, Dalton Trans., 2017, 46, 3921
    DOI: 10.1039/C7DT00441A

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