14580-91-7Relevant academic research and scientific papers
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.
Reactivity of a Sterically Unencumbered α-Borylated Phosphorus Ylide towards Small Molecules
Radius, Michael,Sattler, Ewald,Berberich, Helga,Breher, Frank
, p. 12206 - 12213 (2019/08/30)
The influence of substituents on α-borylated phosphorus ylides (α-BCPs) has been investigated in a combined experimental and quantum chemical approach. The synthesis and characterization of Me3PC(H)B(iBu)2 (1), consisting of small Me substituents on phosphorous and iBu residues on boron, is reported. Compound 1 is accessible through a novel synthetic approach, which has been further elucidated through DFT studies. The reactivity of 1 towards various small molecules was probed and compared with that of a previously published derivative, Ph3PC(Me)BEt2 (2). Both α-BCPs react with NH3 to undergo heterolytic N?H bond cleavage. Different di- and trimeric ring structures were observed in the reaction products of 1 with CO and CO2. With PhNCO and PHNCS, the expected insertion products [Me3PC(H)(PhNCO)B(iBu)2] and [Me3PC(H)(PhNCS)B(iBu)2], respectively, were isolated.
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.
Reactions of Metal Coordinated Carbon Monoxide with Ylides, X. β-Phosphoniocarbene, β-Phosphoniovinyl and Phosphorus Ylide Complexes of Chromium and Cobalt Deriving from Tetramethylphosphonium
Malisch, Wolfgang,Blau, Herbert,Weickert, Peter,Griessmann, Karl-Heinz
, p. 711 - 718 (2007/10/02)
The reaction of Cp(CO)2(NO)Cr with Me3P=CH2 yields tetramethylphosphonium- Me4P (1) via ylide addition at the carbonyl carbon and transylidation.A reversible equilibrium is established between 1 and the starting materials, which is responsible for the facile conversion of 1 into the ylide complex Cp(CO)(NO)Cr-CH2PMe3 (2) on photolysis.In the presence of MeI, 1 is degradated to I, I, I and Cp(CO)2(NO)Cr.Treatment of 1 with an equimolar amount of MeOSO2F leads to the formation of the zwitterionic phosphoniovinyl complexes Cp(CO)(NO)Cr-C(OMe)=CH-PMe3 (3a) and Cp(CO)(NO)Cr-C(OMe)=C(Me)-PMe3 (3b).With excess MeOSO2F the phosphoniocarbene complex SO3F (4a) is obtained.Me3P=CH2 deprotonates 4a to 3b, which adds HCl to give Cl (4b).The phosphonium cobaltacylates Me4P (5a, b), generated from the cobalt complex (CO)2(NO)(L)Co (L = CO, Me3P) and Me3P=CH2, readily transform to the ylide complexes (CO)(NO)(L)Co-CH2PMe3 (6a, b).MeX (X = I, SO3F) cleaves 6b to give (CO)2(NO)(Me3P)Co and X.The new complexes are characterized by elementary analysis and spectroscopy. - Keywords: Carbonmonoxide Conversion, Vinyl Complexes, Carbene Complexes, Ambidentate Nucleophilic Reactivity
