摘要:

A series of Ni(II) complexes with methyl-, ethyl-, andsym-dimethyl-,sym-diethyl-, andsym-di-n-butyl- thioureas and halide, perchlorate, and thiocyanate anions have been prepared and characterized. Spectral and magnetic studies show that compounds NiL4X2(L = N,N′-dimethyl and N,N′-diethylthiourea, X = halide) are tetragonally distorted octahedral species with a singlet ground state and a thermally populated triplet excited state. The remaining compounds are octahedral. Infrared evidence shows sulfur bonding of the disubstituted ligands to the metal, but suggests nitrogen coordination of the methylthiourea compounds.

ISSN:0008-4042    

DOI:10.1139/v68-520

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A summary is presented of a series of investigations of the radiolytic decomposition of ortho- and meta-terphenyl by reactor radiation with varying proportions of fast neutrons and gamma rays and of meta-terphenyl by 1.3 MeV electrons in the temperature range 100 to 450 °C with radiation intensities from 0.01 to 2 Mrads/s. The observations indicate two regions of radiolytic decomposition with a transition zone at 350 to 400 °C. In the lower temperature region,G(decomposition) varied little with temperature, increased with linear energy transfer (l.e.t.), was independent of intensity, and yielded mainly high boiling products. Particular attention was given to the high temperature region, whereG(decomposition) increased rapidly with temperature, was independent of l.e.t., was greater at low intensities than at high intensities, increased with increased pulse frequency for intermittent irradiation, and yielded a greater proportion of benzene and biphenyl. Thermally initiated reaction appeared unimportant except in the absence of radiation. A reaction sequence is given which accounts for these observations in terms of reactions of radical precursors and radicals of the cyclohexadienyl type. A chain reaction occurs in the higher temperature region.

ISSN:0008-4042    

DOI:10.1139/v68-521

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Previous papers in this series investigated the nature of the coordination bond in copper(II) and zinc(II) complexes of 4-substituted pyridines by infrared spectroscopy. In this paper, the investigation has been extended to complexes of 4-methylpyridine with cobalt(II), manganese(II), and nickel(II). The geometry of the solid complexes is assigned, and the force constants associated with the metal–nitrogen bond were calculated from a normal coordinate analysis. The validity of the previously introducedRπparameter in these systems is discussed.

ISSN:0008-4042    

DOI:10.1139/v68-522

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The equilibrium dielectric constants of three isomericN-methylvaleramides are reported over a wide range of temperature. Analysis of the data in terms of Kirkwood's correlation factor suggests that the liquids are extensively associated into linear chains and that the extent of association is essentially independent of the size and shape of the alkyl group. Dielectric dispersion was measured (0.5–200 MHz) for these compounds as well as the isomericN-butylacetamides and alsoN-ethylacetamide. The dispersion loci all follow the Debye equation and the relaxation times show a specific dependence on the size and shape of the alkyl group, but not on whether it is in the acid or the amine position. Activation energies for relaxation, viscous flow, and conduction are compared and the nature of liquidN-mono-substituted amides is discussed.

ISSN:0008-4042    

DOI:10.1139/v68-523

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A general expression is derived for the calculation of total multiplet intensities for radiation emitted from a homogeneous source or transmitted through a homogeneous medium. The theory is then applied to the emission of radiation due to vibration–rotation transitions of HCl in an oven, and compared with experimental results. Absolute values of transition probabilities for individual vibration–rotation lines could be obtained by such a comparison. Another application of the theory is made in obtaining absorption–concentration relationships for the mercury 4358 Å line (73S1–63P1) with several different initial line shapes. The results are compared to absorption − 63P1concentration curves used in earlier work.

ISSN:0008-4042    

DOI:10.1139/v68-524

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Thick-target recoil experiments were performed to study (p,pn) reactions induced in65Cu and197Au in the energy range of 20–85 MeV and the average ranges projected in the forward, backward, and perpendicular directions were determined. Recoil parameters have been calculated to show approximately the amount of energy transfer and their energy dependence. The average range results have been compared with statistical theory, cascade–evaporation (85 MeV only), and inelastic scattering model calculations. The statistical calculations show reasonable agreement up to 30–40 MeV. However, the calculated projected range values, based on the cascade–evaporation and the inelastic scattering models, are consistently lower than the measured values. The analyses of the projected range values support the prevalent view that at low energies (~ 30–35 MeV), the compound nucleus mechanism is predominant and at higher energies, the direct interaction mechanism makes a major contribution.

ISSN:0008-4042    

DOI:10.1139/v68-525

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Absolute values of the cross sections of (p,n), (p,pn), (p,p2n), and (p,p3n) reactions in127I have been measured by radiochemical methods for incident proton of energies up to 80 MeV. The initial portion of the excitation function for the (p,n) reaction is characteristic of the compound nucleus mechanism, but evidence for direct interaction is present at higher energies. Above 50 MeV, cross sections are close to the predictions of Monte Carlo calculations based on the cascade–evaporation model. This is particularly true in the case of the (p,pn) and (p,p2n) reactions.

ISSN:0008-4042    

DOI:10.1139/v68-526

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Spectrofluorometric techniques have been used to determine gas phase singlet and triplet yields in ortho- and para-difluorobenzene as a function of exciting wavelength and pressure. The importance of the "around the corner effect" in such measurements as the cause of large errors is briefly discussed.In the case of ortho-difluorobenzene, maxima in fluorescent yield are produced by the exciting wavelengths 2490, 2580, and 2700 Å; minima at 2540 and 2660 Å. Triplet yields, using the sensitized biacetyl emission technique, have been determined at 2500, 2580, 2660, and 2700 Å. The sums of the singlet and triplet yields at these wavelengths are 0.34, 0.52, 0.75, and 0.97 respectively.Para-difluorobenzene has the largest quantum yield of fluorescence of any fluorinated benzene yet examined. The fluorescent yield shows only one definite minimum at 2740 Å. Triplet yields have been determined at 2660, 2740, and 2760 Å. The sums of the singlet and triplet yields at these wavelengths are 0.5, 0.5, and 0.7 respectively.

ISSN:0008-4042    

DOI:10.1139/v68-527

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A method for the study of preferential solvation in the outer coordination spheres from paramagnetic broadening of solvent proton n.m.r. signals was proposed by Frankel, Stengle, and Langford. It is now extended to determinations of the relative concentrations of water and dioxane, dimethylformamide, or dimethylsulfoxide in the inner coordination spheres of Co2+and Ni2+ions in the binary solvent mixtures. The assumptions of the analysis are cross-checked by a new method based on the contact shifts experienced by protons on solvent molecules in the coordination spheres of paramagnetic ions. The second method depends upon assumptions independent of the first. Three cases are presented as tests of these n.m.r. approaches. It is clear that highly precise solvation sphere populations will be difficult to obtain but that useful and significant information can be obtained in situations to which alternative methods are almost totally inapplicable.The results indicate that dimethylsulfoxide and dimethylformamide are good competitors for coordination sites but that dioxane is excluded by water.

ISSN:0008-4042    

DOI:10.1139/v68-528

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Chlorodicarbonylrhodium dimer ([Rh(CO)2Cl]2) reacted with 2-butyne at 80° in benzene to give a mixture of compounds which contained hexamethylbenzene, duroquinone, chloro(π-duroquinone)-rhodium dimer, and chloro(π-tetramethylcyclopentadienone)rhodium. At 25° 2-butyne and [Rh(CO)2Cl]2reacted to give a brown solid of variable composition (C), which could not be purified. Reaction of (C) with CO in methylene chloride gave a related solid (D) also of variable composition. Treatment of (C), or better (D), with an excess of triphenylphosphine gave chloro(dimethylmaleyl)bis(triphenylphosphine)-rhodium and (Ph3P)2RhCOCl. The former was identified by analysis, spectra, and its oxidation to dimethylmaleic anhydride. Reaction of (D) withp-toluidine gave chloro(dimethylmaleyl)carbonylbis(p-toluidine)rhodium, which on treatment with excess triphenylphosphine also gave chloro(dimethyl-maleyl)bis(triphenylphosphine)rhodium.

ISSN:0008-4042    

DOI:10.1139/v68-529

出版商:NRC Research Press    

年代:1968

数据来源: NRC