Alkali-Metal-Mediated Coupling of a Phosphorus-Substituted Alkene. Structural Characterization of Dilithium 1,1,4,4-Tetrakis(diphenylphosphino)butane-1,4-diide

Clegg, William; Izod, Keith; McFarlane, and William; O‘Shaughnessy, Paul

doi:10.1021/om980741x

Cited by 21 publications

(8 citation statements)

References 26 publications

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“…In contrast to previous reports, 7 we found that, if the reaction between Bu n Li and 2-bromobenzyl methyl ether was allowed to warm to room temperature, a side reaction occurred that greatly diminished the yield of 9. This is most likely due to the formation of butylsubstituted benzyl ethers and LiBr; interestingly, isolation of the expected tertiary phosphine from these reactions yielded a novel tertiary phosphine-LiBr adduct [{(Me 3 Si) 2 CH}P(C 6 H 4 -2-CH 2 OMe) 2 LiBr] 2 (10) as a significant by-product.…”

Section: Resultsmentioning

confidence: 99%

Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

et al. 2005

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The O-functionalised tertiary phosphine {(Me3Si)2CH}P(C6H4-2-CH2OMe)2 (9) is accessible via the reaction of {(Me3Si)2CH}PCl2 with two equivalents of in situ generated 2-LiC6H4CH2OMe. Phosphine 9 is readily deprotonated by Bu(n)Li to give the lithium phosphinomethanide [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]Li] (13), which undergoes metathesis reactions with the alkoxides MOR [M = Na, K, R = Bu(t); M = Rb, R = 2-ethylhexyl] to give the heavier alkali metal phosphinomethanides [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]M]n in good yields [M = Na (14), n= 2; M = K (15), Rb (16), n=[infinity]]. Compounds 9, [{(Me3Si)2CH}P(C6H4-2-CH2OMe)2LiBr]2 (10), and 14-16 have been studied by X-ray crystallography; in the solid state 14 adopts a dimeric structure, whereas 15 and 16 crystallise as one-dimensional polymers.

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Section: Resultsmentioning

confidence: 99%

Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

et al. 2005

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“…Somewhat surprisingly, given that phosphorus-and siliconcontaining substituents stabilise adjacent carbanion centres to a similar extent [the carbanion stabilisation energies of SiH 3 and PH 2 substituents have been calculated as −23.7 and −21.3 kcal mol −1 , respectively], 6 this reaction had not been extended to include phosphorus-substituted alkenes until our recent report. 7 This is in spite of the fact that the Schlenk dimerisation of P-substituted alkenes might be expected to yield highly novel, polyfunctional 1,4-dicarbanions which may additionally provide access to otherwise inaccessible neutral polyphosphines with potential applications in transition metal chemistry and catalysis.…”

Section: Introductionmentioning

confidence: 99%

Complexes of a dianionic bis(diphosphinomethanide) with lithium, sodium, potassium and zirconium. Effect of substitution on the Schlenk dimerisation of vinylidene phosphines

et al. 2004

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The vinylidene phosphine (Pr(n)(2)P)(2)C=CH(2) (1) undergoes Schlenk dimerisation on treatment with an excess of any of the alkali metals Li, Na or K to give the butane-1,4-diide complexes [(L)M{(Pr(n)(2)P)(2)CCH(2)}](2)[(L)M =(THF)(2)Li (6), (THF)(3)Na (7b), (DME)(2)K (8b)], after recrystallisation. Whereas the reaction between the analogous phenyl derivative (Ph(2)P)(2)C=CH(2) and K results in cleavage of a P-C bond, 1 reacts smoothly with K to give 8, with no evidence for P-C cleavage. Compound 6 is an excellent ligand transfer reagent: metathesis reactions between either 6 or its phenyl analogue [(THF)(2)Li{(Ph(2)P)(2)CCH(2)}](2) (2) and two equivalents of Cp(2)ZrCl(2) in THF give the corresponding dinuclear zirconocene derivatives [Cp(2)Zr(Cl){(R(2)P)(2)CCH(2)}](2) in good yields [R = Ph (11), Pr(n)(12)]. Compounds 6, 7b, 8b, 11 and 12 have been characterised by multi-element NMR spectroscopy and, where possible, by elemental analysis; compounds 6, 7b, 11 and 12 have additionally been characterised by X-ray crystallography.

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“…15 We have previously noted that P-C cleavage reactions are competitive with Schlenk dimerisation when (i) the metal is sufficiently reducing, and (ii) the phosphide produced by this side-reaction is sufficiently stabilised. For example, whereas (Ph 2 P) 2 C=CH 2 undergoes facile Schlenk dimerisation on treatment with lithium, 16 treatment of this vinylidene phosphine with potassium yields KPPh 2 as the major phosphorus-containing product. 17 In contrast, the closely related vinylidene phosphine (Pr n 2 P) 2 C=CH 2 undergoes Schlenk dimerisation exclusively when treated with any of the alkali metals Li, Na or K, with no evidence for P-C cleavage.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2009

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A straightforward Peterson olefination reaction between either [{(Me(2)PhSi)(3)C}Li(THF)] or in situ-generated [(Me(3)Si)(2){Ph(2)P(BH(3))}CLi(THF)(n)] and paraformaldehyde gives the alkenes (Me(2)PhSi)(2)C[double bond, length as m-dash]CH(2) () and (Me(3)Si){Ph(2)P(BH(3))}C[double bond, length as m-dash]CH(2) (), respectively, in good yield. Ultrasonic treatment of with lithium in THF yields the lithium complex [{(Me(2)PhSi)(2)C(CH(2))}Li(THF)(n)](2) (), which reacts in situ with one equivalent of KOBu(t) in diethyl ether to give the potassium salt [{(Me(2)PhSi)(2)C(CH(2))}K(THF)](2) (). Similarly, ultrasonic treatment of with lithium in THF yields the lithium complex [[{Ph(2)P(BH(3))}(Me(3)Si)C(CH(2))]Li(THF)(3)](2).2THF (). The bis(phosphine-borane) [(Me(3)Si){Me(2)(H(3)B)P}CH(Me(2)Si)(CH(2))](2) () may be prepared by the reaction of [Me(2)P(BH(3))CH(SiMe(3))]Li with half an equivalent of ClSiMe(2)CH(2)CH(2)SiMe(2)Cl in refluxing THF. Metalation of with two equivalents of MeLi in refluxing THF yields the lithium complex [[{Me(2)P(BH(3))}(Me(3)Si)C{(SiMe(2))(CH(2))}]Li(THF)(3)](2) (), whereas metalation with two equivalents of MeK in cold diethyl ether yields the potassium complex [[{Me(2)P(BH(3))}(Me(3)Si)C{(SiMe(2))(CH(2))}](2)K(2)(THF)(4)](infinity) () after recrystallisation. X-Ray crystallography shows that, whereas the lithium complex crystallises as a discrete molecular species, the potassium complexes and crystallise as sheet and chain polymers, respectively.

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Alkali-Metal-Mediated Coupling of a Phosphorus-Substituted Alkene. Structural Characterization of Dilithium 1,1,4,4-Tetrakis(diphenylphosphino)butane-1,4-diide

Abstract: The butane-1,4-diide salt {(THF)2Li(Ph2P)2CCH2}2 is obtained by treatment of (Ph2P)2CCH2 with lithium in THF; hydrolysis of this salt yields the novel tetraphosphine {(Ph2P)2CHCH2}2.

Cited by 21 publications

References 26 publications

Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

Complexes of a dianionic bis(diphosphinomethanide) with lithium, sodium, potassium and zirconium. Effect of substitution on the Schlenk dimerisation of vinylidene phosphines

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

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