1111-89-3Relevant academic research and scientific papers
Electron distribution in a stable carbene
Arduengo III, Anthony J.,Dias, H. V. Rasika,Dixon, David A.,Harlow, Richard L.,Klooster,Koetzle
, p. 6812 - 6822 (2007/10/02)
The synthesis and characterization of the stable carbene perdeuterio-1,3,4,5-tetramethylimidazol-2-ylidene (2) are reported. The neutron and X-ray diffraction data from single crystals of this perdeuterocarbene are used to determine the electron distribution in the molecule. Neutron diffraction data were collected at 80 and 173K on 2. The experimentally determined electron density is very closely matched by density functional calculations which show that 2 is a true carbene with negligible ylidic character.
Equilibrium Geometry and Vibrational Frequencies of the 1:2 van der Waals Complexes between Methyl Chloride and Hydrogen Chloride
Herrebout, W. A.,Veken, B. J. van der
, p. 3601 - 3608 (2007/10/02)
The equilibrium geometry, relative stability and vibrational frequencies for the 1:2 van der Waals complexes between CH3Cl and HCl have been investigated using MP2/6-31 + G** ab initio calculations.The results are used to interpret the IR spectrum of the 1:2 complex observed in solutions of CD3Cl-HCl mixtures dissolved in liquefied argon, and show that in these solutions the chain complex CD3Cl*HCl*HCl is formed.
Pressure Dependence of the Rate Constants for the Reactions CH3 + O2 and CH3 + NO from 3 to 10E4 Torr
Kaiser, E. W.
, p. 11681 - 11688 (2007/10/02)
A relative rate technique is used to measure the pressure dependence of the rate constants for reaction 1 (CH3 + O2 + M -> CH3O2 + M) and reaction 3 (CH3 + NO + M -> CH3NO + M) relative to reaction 2 (CH3 + Cl2 -> CH3Cl + Cl).The pressure dependence of the rate constant of reaction 3 at 297 K can be represented in the Troe equation by the parameters (k3)0 = (3.5 +/- 0.4)E-30 cm6 molecule-2 s-1, (k3)infinite = (1.68 +/- 0.1)E-11 cm3 molecule-1 s-1, and Fcent = 0.46.The values of k3 are identical to those observed in recent absolute rate measurements at 296 K and 27-600 Torr, verifying that the rate constant chosen for reaction 2, k2 = 3.95E-12 exp(-530/RT), is both pressure independent and correct at 296 K.This value of k2 was used to determine absolute values of k1 from the k1/k2 in N2 diluent for pressures between 3 and 11000 Torr at 297 K, between 20 and 1500 Torr at 370 K, and between 40 and 1500 Torr at 264 K.All data in N2 can be fitted using the following parameters in the Troe equation: (k1)0 = (7.56 +/- 1.1)E-31 (T/300)-3.64+/-1.0 cm6 molecule-2 s-1; (k1)infinite = (1.31 +/- 0.1)E-12 (T/300)1.2+/-0.8 cm3 molecule-1 s-1; Fcent = 0.48 (264 K), 0.46 (297 K), 0.42 (370 K).Error limits include statistical error and the uncertainty in k2.In He, N2, and SF6 diluents the relative third-body efficiencies are 0.56 : 1.0 : 1.52, respectively, assuming that Fcent is independent of diluent.The high-pressure limit in SF6 is identical to that in N2.Rate constant ratios were also measured at 297 K for CD3 + O2 + M -> CD3O2 + M (1D) between 5 and 6000 Torr.Assuming that k2D = k2, the limiting rate constants using Fcent = 0.46 are (k1D)0 = (11.8 +/- 1.6)E-31 cm6 molecule-2 s-1 and (k1D)infinite = (1.38 +/- 0.08)E-12 cm3 molecule-1 s-1.
Kinetics of the gas-phase reactions of Cl with CH3Br and CD3Br: Experimental evidence for nonstatistical behavior?
Viggiano,Morris, Robert A.,Paschkewitz, John S.,Paulson, John F.
, p. 10477 - 10482 (2007/10/02)
The reactions of Cl- with CH3Br and CD3Br have been studied as a function of ion-neutral average center-of-mass kinetic energy, 〈KEcm〉, at several temperatures. The reactions are inefficient, proceeding at only a few percent of the collision rate. Both increasing temperature and increasing kinetic energy are found to decrease the rate constant as approximately T-0.8 or 〈KEcm〉-0.8. The rate constants were found to be independent of pressure at 300 K. At a fixed 〈KEcm〉, no dependence of the rate constants on temperature was found. This indicates that the rate constants for the reactions do not depend on the internal temperature of the CH3Br or CD3Br. By comparison with other systems, we conclude that rotational excitation of the CH3Br should have little effect on the rate constants. Combining the apparent lack of a rotational dependence and the fact that significant amounts of the CH3Br or CD3Br molecules are vibrationally excited leads to the conclusion that the rate constants are also not strongly dependent on vibrational energy.
Darstellung und Struktur von Methylnatrium. Strukturbestimmung an NaCD3-Pulvern bei 1.5 und 300 K durch Neutronen- und Synchrotonstrahlenbeugung
Weiss, Erwin,Corbelin, Siegfried,Cockcroft, Jeremy Karl,Fitch, Andrew Nicholas
, p. 1629 - 1634 (2007/10/02)
Methylsodium (NaCD3) has been obtained by the reaction of methyllithium with sodium tert-butoxide.Its crystal structure has been determined from NaCD3 powder samples using the combination of neutron and synchroton radiation diffraction techniques.Studies at 1.5 and 300 K show a new structure type (orthorhombic, space group I222, Z = 16).Na and C atomic positions have been obtained from synchroton radiation data and subsequently D positions by neutron diffraction.The complete structure has been refined using Rietveld methods. - Half of the ions are arranged in tetramers, (NaCD3)4, similar to those in methyllithium.The orientation of the methanide ions with respect to the three next Na ions is staggered.The remaining 8 Na and 8 methanide ions interconnect the tetramers by Na - C contacts; their Na ions are arranged in zigzag chains.Thus, the structure of methylsodium shows elements of the methyllithium and methylpotassium structure.All methanide ions are trigonal-pyramidal with C -D 109 pm and D - C - D angles of 106 deg (1.5 K).Na - C distances vary from 253 to 291 pm, depending upon the methylNa orientation.IR data of NaCD3 are given.
Ueber Metallalkyl- und -aryl-Verbindungen. XXXVII. Structurverfeinerung von Methylkalium. Darstellung von KCD3 und Neutronbeugungsuntersuchung bei 1.35 und 290 K
Weiss, Ervin,Lambersten, Thomas,Schubert, Bernd,Cockroft, Jeremy Karl
, p. 1 - 14 (2007/10/02)
The crystal structure of methylpotassium has been refined by neutron diffraction carried out on powder samples of KCD3 at 1.35 and 290 K.Pyramidal methyl ions were found with bond angles of 105 deg at 1.35 K and of 109 at 290 K, which are comparable to those of NH3.In the crystal the methyl ions have alternating orientations and each carbanion is coordinated by six K ions in a distorted trigonal-prismatic array.The three K ions close to the sp3 lone electron pair have short K-C contacts (2 * 295,1 * 302 ppm), whereas the K ions close to the H atoms have longer K-C distances (2 * 344,1 1 * 330 pm).An orthorhombic unit cell (Pmcn, Nr 62, a 419.56(2), b 730.73(3), c 816.44(3) pm, Z = 4, 1.35 K) has now been found as compared to the smaller hexagonal cell (Z = 2) detected previously by X-ray metods (without precise location of the H atoms).The preparation of KCD3 and LiCD3 is described and IR data of KCD3 are given.
Onium Ylide Chemistry. 4. Alkylhalonium Methylides
Olah, George A.,Doggweiler, Hans,Felberg, Jeff D.
, p. 4975 - 4978 (2007/10/02)
Alkylhalonium methylides were generated by two independent routes, proving their formation through derived product analysis.The reaction of singlet methylene, produced by photolysis of diazomethane, with methyl and ethyl halides gives in competition with C-H insertion evidence of methylenation of halogen atom, i.e., alkylhalonium methylide formation.The unstable halonium methylides are immediatly protonated or alkylated in the reaction medium to give dialkylhalonium ions which then undergo cleavage to the corresponding alkyl halides.Methyliodonium methylide was also generated via the deprotonation of dimethyliodonium hexafluoroantimonate with sodium hydride in competition with the expected methylation of fluoride and hydride, giving the major products.Subsequent methylation of the methyliodonium methylide by excess dimethyliodonium ion gives methylethyliodonium ion followed by cleavage leading to the formation of ethyl halides and via hydride reduction to ethane, respectively.Attempted formation of alkylhalonium methylides via fluoride cleavage of methylhalonium hexafluoroantimonates was unsuccessful due to ready disproportionation of the halonium ions.
