676-49-3Relevant articles and documents
Absoption and Reactions of Methanethiol on Clean and Modified Ni(110)
Huntley, D. R.
, p. 6156 - 6164 (1989)
The reactions of methanethiol on clean and modified Ni(110) have been studied under ultrahigh-vacuum conditions by temperature-programmed reactions (TPR), including deuterium incorporation studies.Surface bound molecular fragments were identified by X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS).The TPR data indicate that the major products of the reactions of methanethiol with clean Ni(110) surfaces are methane and hydrogen.Methane desorbs in a reaction-limited peak at 276 K, which does not shift with methanethiol exposure.Hydrogen desorption occurs in several peaks depending on the exposure.The coverage dependence of the methane yield indicates a competition between decomposition and reaction to form methane.At low coverages, decomposition is the major pathway while at higher coverages methane formation dominates.Vibrational spectroscopy (HREELS) indicates the presence of the methyl thiolate intermediate at temperatures less than 200 K.X-ray photoelectron spectroscopy and deuterium incorporation experiments confirm this assignment.A mechanism has been proposed based on hydrogenolysis of the methyl thiolate species and is consistent with all of the data.The appropriate rate equations associated with this mechanism have been solved numerically to predict the TPR data, and qualitative agreement was achieved .Methanethiol reacts with sulfur- and oxigen-modified Ni(110) surfaces to produce methane, hydrogen, and, in the case of the oxidized surfaces , water.The major effect of the modifier was to enhance the formation of methane relative to decomposition.These observations can be explained by either electronic or structural effects.
H/D exchange between CH4 and CD4 catalysed by a silica supported tantalum hydride, (?SiO)2Ta-H
Lefort, Laurent,Coperet, Christophe,Taoufik, Mostafa,Thivolle-Cazat, Jean,Basset, Jean-Marie
, p. 663 - 664 (2000)
The silica supported tantalum hydride (?SiO)2Ta-H 1, catalyses the H/D exchange reaction between CH4 and CD4 at 150 °C producing the statistical distribution of all methane isotopomers.
Reactivity of Tricyclopentadienyl Uranium Tetrahydroaluminate
Ossola, Franco,Brianese, Nicola,Porchia, Marina,Rossetto, Gilberto,Zanella, Pierino
, p. 877 - 880 (1990)
The reactivity of (1) (cp = η5-C5H5) has been studied.With (CH3)3CNC it gives >, with pyridine , with CH3CN and , with (CH3)3CNCO, which probably inserts into
Interaction of gaseous D atoms with alkyl halides adsorbed on Pt(111), H/Pt(111), and C/Pt(111) surfaces: Hot-atom and Eley-Rideal reactions. I. Methyl bromide
Wehner,Kueppers
, p. 3209 - 3217 (1999)
The interaction of gaseous D atoms with methyl bromide molecules adsorbed on Pt(111), hydrogen saturated Pt(111), and graphite monolayer covered Pt(111) surfaces was studied in order to elucidate the reaction mechanisms. The reaction kinetics at 85 K surface temperature were measured as a function of the methyl bromide precoverage by monitoring reaction products simultaneously with D atom exposure. On all substrates incoming atoms abstract the methyl group from adsorbed CH3Br via gaseous CH3D formation. In the monolayer regime of CH3Br/Pt(111) pure hot-atom phenomenology was observed in the rates. At multilayer targets the fluence dependence of the kinetics gets Eley-Rideal-like. With coadsorbed H present, the reaction of D with adsorbed methyl bromide revealed in addition to CH3D a CH4 product. This and simultaneous abstraction of adsorbed H via gaseous HD and H2 products clearly demonstrates that hot-atom reactions occur. At CH3Br adsorbed on a graphite monolayer on Pt(111) the abstraction kinetics of methyl was found to agree with the operation of an Eley-Rideal mechanism. These observations are in line with the expectation that hot-atoms do not exist on a CTPt(111) surface but on Pt(111) and H/Pt(111) surfaces. The methyl abstraction cross-sections in the monolayer regime of methyl bromide were determined as about 0.25 A2, irrespective of the nature of the substrate. This value is in accordance with direct, Eley-Rideal or hot-atom reactions.
On the Mechanism of Base-catalysed Alkane-forming Reactions of Simple Alkylcobaloximes
Brown, Kenneth L.
, p. 598 - 599 (1981)
From the time dependence of the formation of monodeuterioalkanes in D2O, and related isotopic labelling experiments, the base-catalysed alkane-forming reactions of ethyl- and methyl-(aquo)cobaloximes have been found to occur via different mechanisms.
Axial Donor Effects on Oxidatively Induced Ethane Formation from Nickel-Dimethyl Complexes
Smith, Sofia M.,Rath, Nigam P.,Mirica, Liviu M.
supporting information, p. 3602 - 3609 (2019/10/11)
Tetradentate pyridinophane ligands have been shown to stabilize uncommon high-valent palladium and nickel organometallic complexes. Described herein are the synthesis and detailed characterization of a series of NiII- and NiIII-dimethyl complexes supported by modified tetradentate pyridinophane ligands in which one or both of the N-methyl substituents were replaced with electron-withdrawing p-toluenesulfonyl groups, thus reducing the amine N atom donicity and favoring the formation of Ni complexes with lower coordination numbers. The corresponding NiII-dimethyl complexes exhibit accessible oxidation potentials, and their oxidation generates NiIII species that were characterized by EPR and X-ray crystallography. Moreover, the NiII-dimethyl complexes exhibit selective ethane formation upon oxidatively induced reductive elimination using various oxidants - including O2 and H2O2, without the generation of any C-heteroatom products. Overall, these results suggest that the (RN4)NiIIMe2 complexes with more weakly donating axial ligands are more reactive toward ethane formation, likely due to destabilization of the corresponding high-valent Ni intermediates and formation of 5- and 4-coordinate conformations for these Ni species.
Mechanistic study of the rhodium-catalyzed carboxylation of simple aromatic compounds with carbon dioxide
Suga, Takuya,Saitou, Takanobu,Takaya, Jun,Iwasawa, Nobuharu
, p. 1454 - 1462 (2017/02/10)
A detailed mechanism of the Rh(i)-catalyzed carboxylation of simple aromatic compounds via C-H bond activation was investigated. Kinetic studies with model compounds of the postulated key intermediates revealed that 14-electron complexes, RhMe(dcype) and RhPh(dcype), participated in the C-H bond activation step and the carboxylation step, respectively. Interestingly, the undesired carboxylation of RhMe(dcype) to give acetic acid was found to be much faster than the desired C-H bond activation reaction under stoichiometric conditions, however, the C-H bond activation reaction could occur under catalytic conditions. Careful controlled experiments revealed that C-H bond activation using RhMe(dcype) became competitive with its direct carboxylation under the condition that the concentration of CO2 in the liquid phase was rather low. This factor could be controlled to some extent by mechanical factors such as the stirring rate and the shape of the reaction vessel. The resting state of the rhodium species under catalytic conditions was found to be [RhCl(dcype)]2, and the proposed intermediates such as RhMe(dcype) and Rh(OBz)(dcype) were readily converted to the most stable state, [RhCl(dcype)]2, via transmetallation with [Al]-Cl species, thus preventing the decomposition of the active catalytic species.
