Synthesis of α-, γ-phosphorus functionalized alkyl lithium species; X-ray structures of [{Li(L)(CH2PMeR)}2] [L = NNN′N′-tetramethylethylenediamine(tmen), R = Me or Ph; L = (-)sparteine, R = Ph] and [Li(tmen){CH(SiMe3)C6H4PPh2-o}]

Lindsay T. Byrne, Lutz M. Engelhardt, Geraldine E. Jacobsen, Wing Por Leung, Rocco I. Papasergio, Colin L. Raston, Brian W. Skelton, Paul Twiss, Allan H. White

Research output: Contribution to journalArticle

Abstract

[{Li(L)(CH2PMeR)}2] [L = tetramethylethylenediamine (tmen), R = Me (1) or Ph (2); L = (-)-sparteine (sp), R = Ph (3)], prepared by treating the appropriate phosphine with LiBun(L) in hexane or diethyl ether, are dimeric in the solid. The phosphinomethyl ligands bridge the two lithium atoms as part of six-atom heterocycles; Li-C, P 2.145, 2.604; 2.14, 2.64; 2.20, 2.72 Å, respectively; (2) and (3) are homochiral and thus have a meso configuration. In benzene (1), (2), and [Li(tmen)(CH2PPh2)] (5), are monomeric (cryoscopy), and 7Li-31P coupling only below ca. -70 °C for (1)-(3) and (5) in toluene (1:1 doublet, 7Li; 1:1:1:1 quartet, 31P, JLiP 44.0-53.4 Hz) is consistent with the presence of symmetrical dimers of the type found in the solid for (1)-(3). [Li(tmen){CH(SiMe3)C6H4PPh2-o}], (4), similarly prepared, has the lithium as part of a chelate ring in the solid, binding through the ipso carbon and PIII centre; Li-C,P 2.25(1), 2.65(1) Å. Trilithio species based on P(C6H4CHR-)3 (R = H or SiMe3) are generated via metallation using LiBun(tmen). Treating the monolithio species derived from P(O)Me2Ph and LiBun(sp) with EtI yields P(O)MePhPrn of 14% estimated optical purity.

Original languageEnglish
Pages (from-to)105-113
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number1
DOIs
Publication statusPublished - Jan 1989
Externally publishedYes

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