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Issue 17, 2009
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Synthesis and structural characterisation of alkali metal complexes of heteroatom-stabilised 1,4- and 1,6-dicarbanions

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Abstract

A straightforward Peterson olefination reaction between either [{(Me2PhSi)3C}Li(THF)] or in situ-generated [(Me3Si)2{Ph2P(BH3)}CLi(THF)n] and paraformaldehyde gives the alkenes (Me2PhSi)2C[double bond, length as m-dash]CH2 (1) and (Me3Si){Ph2P(BH3)}C[double bond, length as m-dash]CH2 (2), respectively, in good yield. Ultrasonic treatment of 1 with lithium in THF yields the lithium complex [{(Me2PhSi)2C(CH2)}Li(THF)n]2 (3), which reacts in situ with one equivalent of KOBut in diethyl ether to give the potassium salt [{(Me2PhSi)2C(CH2)}K(THF)]2 (4). Similarly, ultrasonic treatment of 2 with lithium in THF yields the lithium complex [[{Ph2P(BH3)}(Me3Si)C(CH2)]Li(THF)3]2.2THF (5). The bis(phosphine-borane) [(Me3Si){Me2(H3B)P}CH(Me2Si)(CH2)]2 (6) may be prepared by the reaction of [Me2P(BH3)CH(SiMe3)]Li with half an equivalent of ClSiMe2CH2CH2SiMe2Cl in refluxing THF. Metalation of 6 with two equivalents of MeLi in refluxing THF yields the lithium complex [[{Me2P(BH3)}(Me3Si)C{(SiMe2)(CH2)}]Li(THF)3]2 (9), whereas metalation with two equivalents of MeK in cold diethyl ether yields the potassium complex [[{Me2P(BH3)}(Me3Si)C{(SiMe2)(CH2)}]2K2(THF)4] (10) after recrystallisation. X-Ray crystallography shows that, whereas the lithium complex 5 crystallises as a discrete molecular species, the potassium complexes 4 and 10 crystallise as sheet and chain polymers, respectively.

Graphical abstract: Synthesis and structural characterisation of alkali metal complexes of heteroatom-stabilised 1,4- and 1,6-dicarbanions

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Publication details

The article was received on 09 Dec 2008, accepted on 16 Feb 2009 and first published on 12 Mar 2009


Article type: Paper
DOI: 10.1039/B822054A
Citation: Dalton Trans., 2009, 3340-3347
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    Synthesis and structural characterisation of alkali metal complexes of heteroatom-stabilised 1,4- and 1,6-dicarbanions

    K. Izod, L. J. Bowman, C. Wills, W. Clegg and R. W. Harrington, Dalton Trans., 2009, 3340
    DOI: 10.1039/B822054A

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