14580-91-7Relevant articles and documents
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Stein,J.,Fackler,J.P.,Paparizos,C.
, p. 2192 (1981)
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Formation and stability of organic zwitterions - The carbon acid pK as of the trimethylsulfonium and tetramethylphosphonium cations in water
Rios, Ana,O'Donoghue, AnnMarie C.,Amyes, Tina L.,Richard, John P.
, p. 1536 - 1542 (2005)
We report second-order rate constants of kDO = 7.5 × 10-4 and 9.9 × 10-5 (mol/L)-1 s -1 for exchange for deuterium of the first methyl proton of the trimethylsulfonium and tetramethylphosphonium cations, respectively, in D 2O at 25°C and 1 = 1.0 (KCl). The data were analyzed to give the following carbon acidities for these cationic carbon acids in water: (CH 3)3S+, pKa = 28.5; (CH 3)4P+, pKa = 29.4. These acidities are close to those of the neutral carbon acids acetonitrile and dimethylacetamide. This provides evidence that a portion of the stabilization of the cyanomethyl carbanion is due to resonance delocalization of negative charge from carbon to cyano nitrogen.
Synthesis and reactivity of [M(η3-allyl)(η2-amidinato)(CO)2(phosphonium ylide)] (M?=?Mo, W): Investigation of the ligand properties of phosphonium ylides
Takaki, Daichi,Ogata, Kenichi,Kurihara, Youji,Ueda, Kazuyoshi,Hashimoto, Toru,Yamaguchi, Yoshitaka
, p. 310 - 315 (2017/11/27)
Phosphonium ylide complexes of Mo and W formulated as [M(η3-allyl){η2-(NPh)2CH}(CO)2(CH2PR3)] (M = Mo, R = Me: 2a-Mo; M = Mo, R = Ph: 2b-Mo, and M = W, R = Me: 2a-W) were prepared by the reaction of amidinato(pyridine) complex, [M(η3-allyl){η2-(NPh)2CH}(CO)2(NC5H5)] (M = Mo: 1-Mo and M = W: 1-W), with a phosphonium ylide, CH2PR3 (R = Me, Ph), which was generated in situ by the reaction of the corresponding phosphonium salt with nBuLi. These complexes were characterized spectroscopically, as well as by the X-ray diffraction. The phosphonium ylide ligand shows stronger electron donating ability toward the metal than N-heterocyclic carbene or phosphine ligands. This trend is supported by the comparison of the spectroscopic data and the DFT calculations. We also investigated the reactivity of the phosphonium ylide complexes 2-Mo with two-electron donors such as PEt3 and NHC. In the case of the PPh3 ylide complex (2b-Mo), the substitution reaction of the ylide ligand for the two-electron donors took place cleanly to yield the corresponding complexes. On the other hand, in the PMe3 ylide complex (2a-Mo), the substituted complexes formed but the unreacted ylide complex 2a-Mo was also present in the reaction mixture. These results show that the bond strength of the M-C(phosphonium ylide) bond is affected by the substituents on the phosphorus atom.
