15439-85-7Relevant academic research and scientific papers
Bis(tert-butylimido)bis(N,O-chelate)tungsten(VI) Complexes: Probing Amidate and Pyridonate Hemilability
Clarkson, Joseph M.,Schafer, Laurel L.
, p. 5553 - 5566 (2017)
Four new bis(tert-butylimido)bis(N,O-chelate)tungsten(VI) complexes (3-6), in which the N,O-chelate is an amidate or pyridonate ligand, have been synthesized and characterized. Computational analysis has been used to calculate the relative energies of different stereoisomers and shown how the steric demand of each ligand influences coordination and bonding modes. The electronically saturated complexes have been employed to evaluate 1,3-N,O-chelated metal-ligand interactions. Complexes 3-6 were treated with electrophilic reagents, which resulted in strikingly different reactivity patterns between the amidate and the pyridonate ligated complexes. The observed reactivity differences are accompanied by direct observation of different trends in the hemilability of these two different classes of 1,3-N,O-chelates.
Frustrated Lewis Pair Mediated 1,2-Hydrocarbation of Alkynes
Fasano, Valerio,Curless, Liam D.,Radcliffe, James E.,Ingleson, Michael J.
supporting information, p. 9202 - 9206 (2017/07/25)
Frustrated Lewis pair (FLP) chemistry enables a rare example of alkyne 1,2-hydrocarbation with N-methylacridinium salts as the carbon Lewis acid. This 1,2-hydrocarbation process does not proceed through a concerted mechanism as in alkyne syn-hydroboration, or through an intramolecular 1,3-hydride migration as operates in the only other reported alkyne 1,2-hydrocarbation reaction. Instead, in this study, alkyne 1,2-hydrocarbation proceeds by a novel mechanism involving alkyne dehydrocarbation with a carbon Lewis acid based FLP to form the new C?C bond. Subsequently, intermolecular hydride transfer occurs, with the Lewis acid component of the FLP acting as a hydride shuttle that enables alkyne 1,2-hydrocarbation.
Catalytic formation of ammonia from molecular dinitrogen by use of dinitrogen-bridged dimolybdenum-dinitrogen complexes bearing pnp-pincer ligands: Remarkable effect of substituent at pnp-pincer ligand
Kuriyama, Shogo,Arashiba, Kazuya,Nakajima, Kazunari,Tanaka, Hiromasa,Kamaru, Nobuaki,Yoshizawa, Kazunari,Nishibayashi, Yoshiaki
supporting information, p. 9719 - 9731 (2014/07/22)
A series of dinitrogen-bridged dimolybdenum-dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system.
Access to a CuII-O-CuII motif: Spectroscopic properties, solution structure, and reactivity
Haack, Peter,Kaergel, Anne,Greco, Claudio,Dokic, Jadranka,Braun, Beatrice,Pfaff, Florian F.,Mebs, Stefan,Ray, Kallol,Limberg, Christian
supporting information, p. 16148 - 16160 (2013/11/19)
We report a complex with a rare CuII-O-CuII structural motif that is stable at room temperature, which allows its in-depth characterization by a variety of spectroscopic methods. Interest in such compounds is fueled by the recent discovery that a CuII-O-Cu II species on the surface of Cu-ZSM-5 is capable of oxidizing methane to methanol, and this in turn ties into mechanistic discussions on the methane oxidation at the dicopper site within the particulate methane monooxygenase. For the synthesis of our Cu2O complex we have developed a novel, neutral ligand system, FurNeu, exhibiting two N-(N′,N′-dimethylaminoethyl) (2-pyridylmethyl)amino binding pockets connected by a dibenzofuran spacer. The reaction of FurNeu with CuCl yielded [FurNeu](Cu2(μ-Cl))(CuCl 2), 1, demonstrating the geometric potential of the ligand to stabilize Cu-X-Cu moieties. A CuI precursor with weakly coordinating anions was chosen in the next step, namely [Cu(NCCH3) 4]OTf, which led to the formation of [FurNeu](Cu(NCCH 3))2(OTf)2, 3. Treatment of 3 with O 2 or PhIO led to identical green solutions, whose UV-vis spectra were markedly different from the one displayed by [FurNeu](Cu)2(OTf) 4, 4, prepared independently from FurNeu and Cu(OTf)2. Further investigations including PhIO consumption experiments, NMR and UV-vis spectroscopy, HR-ESI mass spectrometry, and protonation studies led to the identification of the green product as [FurNeu](Cu2(μ-O))(OTf) 2, 5. DOSY NMR spectroscopy confirmed its monomeric character. Over longer periods of time 5 decomposes to give [Cu(picoloyl)2], formed through an oxidative N-dealkylation reaction followed by further oxidation of the ligand. Due to its slow decomposition reaction, all attempts to crystallize 5 failed. However, its structure in solution could be determined by EXAFS analysis in combination with DFT calculations, which revealed a Cu-O-Cu angle that amounts to 105.17. Moreover, TDDFT calculations helped to rationalize the UV-vis absorptions of 5. The reactivity of complex 5 with 2,4-di-tert- butylphenol, DTBP, was also investigated; the initially formed biphenol product, TBBP, was found to further react in the presence of excessive O2 to yield 2,4,7,9-tetra-tert-butyloxepino[2,3-b]benzofuran, TBOBF, via an intermediate diphenoquinone. It turned out that 5, or its precursor 3, can even be employed as a catalyst for the oxidation of DTBP to TBBP or for the oxidation of TBBP to TBOBF.
Acidolyis and oxygen atom transfer reactivity of a diiridium hydroperoxo complex
Teets, Thomas S.,Nocera, Daniel G.
, p. 3521 - 3527 (2013/04/10)
Oxygenation of Ir2II,II(tfepma)2(CN tBu)2Cl3H (1, tfepma = CH 3N[P(OCH2CF3)2]2) furnishes Ir2II,II(tfepma)2(CN tBu)2Cl3(OOH) (2), the first isolable iridium hydroperoxo complex. This complex transfers an oxygen atom to triphenylphosphine, producing triphenylphosphine oxide and Ir2 II,II(tfepma)2(CNtBu)2Cl 3(OH) (3) in high yield. Reaction of 2 with acid induces cleavage of the O-O bond, initially forming [Ir2II,II(tfepma) 2(CNtBu)2Cl3(OH2)]Cl (4), which was identified by NMR spectroscopy. With HCl as the acid source, the chloride anion displaces water to form the pseudo-C2h isomer of Ir2II,II(tfepma)2(CNtBu) 2Cl4 (5). With 2,6-lutidinium chloride as the acid, complex 4 forms initially and is deprotonated by the conjugate base to afford 3 as the major product.
Effect of tertiary amines on the hydrolysis kinetics of benzoyl chloride in water-dioxane solutions
Batiha, Mohammad A.,Chizhova, Elena A.,Batiha, Marwan M.
, p. 4087 - 4090 (2013/05/21)
The main object of this study was to study the effect of pyridine, 2-methyl pyridine, 3-methyl pyridine, 2,6-dimethyl pyridine, quinoline and tribenzylamine on the hydrolysis kinetics of benzoyl chloride in water-dioxane solutions. The investigation has b
Metal-free carbon dioxide reduction and acidic C-H activations using a frustrated Lewis pair
Tran, Sophia D.,Tronic, Tristan A.,Kaminsky, Werner,Michael Heinekey,Mayer, James M.
experimental part, p. 126 - 132 (2011/06/24)
Activation of CO2 and acidic C-H bonds by the lutidine-tris(pentafluorophenyl)borane [Lut/B(C6F5) 3] frustrated Lewis pair (FLP) are described (lutidine = 2,6-dimethylpyridine). Lut/B(C6F5)
Suppression of common-ion return by amines: A method to measure rates of fast SN1 reactions
Streidl, Nicolas,Antipova, Anna,Mayr, Herbert
supporting information; experimental part, p. 7328 - 7334 (2010/01/16)
(Chemical Equation Presented) Rate constants for solvolyses of benzhydryl chlorides, which take place on the 10 ms to minute time scale, have been determined in aqueous acetone and acetonitrile by conductometry, using conventional conductometers as well as stopped-flow techniques. Secondary and tertiary amines were used to suppress ion recombination (common-ion return) thus giving access to the ionization rate constants k1. The observed common-ion rate depressions can be rationalized by the correlation equation for electrophile-nucleophile combinations, log k(20 °C) = s(E + N), where electrophiles (here: carbocations) are characterized by the parameter Eand nucleophiles (here: chloride anions and solvents) are characterized by N and s. 2009 American Chemical Society.
PROCESS FOR PREPARING GEMCITABINE AND ASSOCIATED INTERMEDIATES
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Page/Page column 10; 11, (2008/06/13)
The present invention provides novel intermediates, which preferably include 3-substituted, alkyl 2,2-difluoro-3-hydroxy-3-(2,2-dialkyldioxolan-4-yl)-propionate derivatives, and 3,5-disubstituted-2-deoxy-2,2-difluoro-1-oxo-D-ribose derivatives. The presen
