摘要:

The adiabatic rapid passage (ARP) technique was applied to the study of molecular motion in solids. Second moments and spin–lattice relaxation times for solid furan and benzene were derived using ARP methods from 77 °K to the respective melting points. Unusual variations of the ARP signal height and shape with temperature were observed for these solids. These effects were interpreted as being due to the presence of short rotating frame relaxation times. New information regarding molecular motion in solid furan, as well as acetic acid-d1, was obtained. Also some quantitative statements have been made regarding the conditions required to observe an ARP signal in the solid state.

ISSN:0008-4042    

DOI:10.1139/v74-031

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The structure of dinitrato(triphenylphosphine)mercury(II), Hg(N03)2.P(C6H5)3, has been determined from single–crystal X-ray data measured on a computer–controlled diffractometer. The crystals are monoclinic, have a unit cell of dimensionsa = 10.39(1),b = 9.56(1),c = 19.44(2) Å, β = 94.3(1)°, which contains 4 molecules, and they belong to the space group,P21/c. The structure has been refined by least–squares methods from 2470 independent observed reflections to a conventionalR-factor of 0.061. The Hg atom has a distorted tetrahedral coordination with Hg—O bond lengths of 2.190(8), 2.428(8), and 2.560(9) Å and an Hg—P bond distance of 2.359(3) Å. There are 2 distinct types of NO3groups bonded to Hg. One is an unshared, unidentate ligand and the other acts as a bridging group joining 2 Hg atoms. Chains of—Hg—NO3—Hg—atoms are formed which follow crystallographic two-fold screw axes in theb-direction.

ISSN:0008-4042    

DOI:10.1139/v74-032

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Enthalpies of solution of LiCl, NaCl, (CH3)4NBr, (C2H5)4NBr, (C3H7)4NBr, and (C4H9)4NBr in dioxane-water mixtures varying in composition from 20 to 64.5% dioxane have been determined. Values of standard enthalpy of solution, ΔHs0, were obtained using the extended Debye–Hückel equation.Using these ΔHs0and the lattice energies (U) of these salts, solvation enthalpies have been evaluated.

ISSN:0008-4042    

DOI:10.1139/v74-033

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The β-L-fucopyranosyl chloride 2,3,4-tri(chlorosulfate) (1) has been prepared by reaction of sulfuryl chloride withL-fucose at low temperature (yield, 47%). This β-L-fucopyranosyl chloride (1) gave high yields of the α-L-fucoside by reaction with alcohols. Thep-nitrobenzyl α-L-fucoside has been prepared (yield, 35%). FromL-fucose, the α-L-fucoside is obtained in three steps.

ISSN:0008-4042    

DOI:10.1139/v74-034

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The infrared and Raman spectra of the hexacarbonylmanganese cation as Mn(CO)6+PF6−were assigned by comparison with other hexacarbonyl species. The CO stretching force constants for Mn(CO)6+and Re(CO)6+as indicated by the CO stretching vibrational frequencies are not significantly different. However, the Mn—C force constant in Mn(CO)6+is likely to be considerably less than the Cr—C force constant in Cr(CO)6, whereas Re(CO)6+and W(CO)6have similar values. It is postulated that, although Mn(CO)6+has equal metal–carbon σ bonding to Re(CO)6+, the metal-carbon σ bonding is less for Mn(CO)6+.

ISSN:0008-4042    

DOI:10.1139/v74-035

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The rates of pyrolysis of cyclopropane in nitrogen have been determined using a wall-less reactor at temperatures of 600–740 °C and a total pressure of 1 atm. In the presence of oxidized stainless steel. quartz, or carbon coated steel rods the rate of conversion to propylene is 1.9 times the rate under homogeneous conditions. A maximum in surface effect was observed atS/V = 0.6 cm−1. A small but increased amount of methane and ethene are formed under surface conditions as compared to homogeneous conditions. Several possible mechanisms for the rate enhancement by surface are discussed. The most likely possibility is surface interaction with the cyclopropane molecule to form the diradical followed by its surface promoted conversion to propene. The importance of determining surface effects by comparing surface rates withtotallyhomogeneous rates is emphasized.

ISSN:0008-4042    

DOI:10.1139/v74-036

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The radiolysis of ethane has been studied over the density range 0.0018–0.5 g cc−1at a temperature just above the critical point. The variations of product yields with increasing density are consistent with increasing collisional stabilization of excited species. Electron scavenging by sulfurhexafluoride in ethane at 0.275 g cc−1is accurately described by an expression used for liquid phase scavenging with Gfree ions = 0.65. At 0.052 g cc−1a much higher yield of free ions is observed and at high sulfurhexafluoride concentrations there is a sensitized decomposition of ethane.Ammonia-d3scavenges ions at all densities but in the region around 0.07 g cc−1a mechanism operates which produces more than one hydrogen molecule per ion scavenged. The freely diffusing ions do not appear to be readily scavenged by ammonia-d3.

ISSN:0008-4042    

DOI:10.1139/v74-037

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The interaction of the monobasic protonic acids HSO3F, HSO3CH3, HPO2F2, and HCO2CF3with titanium(IV) chloride at room temperature is studied with either the acid or the metal halide in excess. Whereas with the acid in excess products of the type TiCl2Y2, with Y = oxyacid group, are formed, the excess of TiCl4results in the formation of TiCl3.33(SO3F)0.66, TiCl3SO3CH3, and again TiCl2(PO2F2)2and TiCl2(CO2CF3)2.The first two compounds are also obtained by ligand redistribution reactions with TiCl4in excess,e.g.in quantitative yield.Vibrational spectra for the PO2F2, SO3F and the previously reported SO3CF3derivatives are interpreted in terms of hexacoordinated titanium and generally bi- or tridentate oxyacid groups. In TiCl3.33(SO3F)0.66evidence for a highly unusual tetradentate SO3F group is presented, where coordination to titanium involves all three oxygens as well as fluorine.

ISSN:0008-4042    

DOI:10.1139/v74-038

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Rate constants for the quenching of O2(1Σg+) in the gas phase have been determined for 12 aliphatic hydrocarbons. The values are discussed in terms of a mechanism in which the magnitudes of the rate constants are determined by the abilities of the quenchers to become vibrationally excited when O2(1Σg+)is relaxed to O2(1Δg).The resulting equations are tested quantitatively by relating the rate constants to the absorption spectra of the quenchers at the frequencies of the O2(1Σg+−1Δg) transition.

ISSN:0008-4042    

DOI:10.1139/v74-039

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The thermal decomposition of 3-chloro and 3-bromo-3-ethyldiazirine in various solvents has been investigated. A comparison was made between the decomposition in gas phase and in solution. The nature of the solvent does not affect the rate of diazirine decomposition, but does alter the subsequent reactions of the carbene. The results show that thecisolefin is predominant in a non-polar solvent but less so in polar solvent. These results were successfully explained by considering the electrostatic interaction of the CH3δ+and Clδ−groups.

ISSN:0008-4042    

DOI:10.1139/v74-040

出版商:NRC Research Press    

年代:1974

数据来源: NRC