Département de chimie moléculaire

Addn. of two equiv. of (Me3Si)2CLiCl to the C-[(diphenyl)(diisopropylamino)phosphonio]-P-(diisopropylamino)phosphaalkene {\{}2; [iPr2NP:CHPPh2(NiPr2)][BF4]{\}} affords the 1$\sigma$4,3$\sigma$3-diphosphabuta-1,2,3-triene {\{}E1; (TMS)2C:P(NiPr2):C:PPh2(NiPr2){\}} in 55{%} yield. Deriv. E1 was fully characterized, including a single-crystal x-ray diffraction study. Alkylation of E1 with MeOTf gives rise to the 1st C-phosphonio-bis(methylene)phosphorane {\{}5, [(TMS)2C:P(NiPr2):CMePPh2(NiPr2)]OTf{\}} which was isolated in 84{%} yield. Because the 2nd C center is also nucleophilic, cumulene E1 reacts as a pincer with BF3·OEt2, giving a novel four-membered CBCP heterocycle {\{}6; (TMS)2C-BF2-C(PPh2(NiPr2))-PF(NiPr2){\}} with a betaine-like structure. Addn. of three equiv. of P-[diphenyl(diisopropylamino)]methylene phosphorane to (diisopropylamino)dichlorophosphine, followed by addn. of one equiv. of CCl4, and subsequent deprotonation with LiN(TMS)2 gave rise to 1$\sigma$4,3$\sigma$3,5$\sigma$4-triphosphapenta-1,2,3,4-tetraene {\{}F1; Ph2(iPr2N)P:C:P(NiPr2):C:PPh2(NiPr2){\}}, which was isolated in 62{%} yield. [on SciFinder(R)]