bluuebunny/crossref_metadata_2025 huggingface dataset:
Sorption of dimethyl ether on silica gel
Authors: Robinson E. , Ross R. A.
Published: May 2006

The adsorption of dimethyl ether has been studied at its boiling point on a range of silica gels by measurement of adsorption/desorption isotherms and isothermal calorimetric heats of adsorption. Data were determined on gels heat treated at 240, 500, 700, and 900 °C and also on gels impregnated with 0.274% w/w aluminum. On 240 °C gels, heats of adsorption varied from around 20 through 12 to 7 kcal/mole at θ = 0.01, 0.50, and 0.90, respectively. Hysteresis loops are analyzed and the initial adsorption trends explained by hydrogen bond formation between the ether oxygen and surface hydroxy groups. The enhanced amounts of ether adsorbed after aluminum impregnation are explained by the creation of either Brønsted acid sites on gels treated at 240 °C or Lewis acid sites on gels treated at the highest temperatures.
Molar excess enthalpies and volumes of cyclohexane – isomeric decalin systems at 25 °C
Authors: Benson G. C. , Murakami S. , Lam V. T. , Singh Jaswant
Published: May 2006

The molar excess enthalpies and volumes of the systems cyclohexane – cis-decalin and cyclohexane – trans-decalin at 25 °C were determined by direct calorimetric and dilatometric measurements. The Flory theory of mixtures provides a useful basis for a qualitative interpretation of the results.
Infrared and Raman spectra of liquid and crystalline silicon tetrafluoride
Authors: Bessette F. , Cabana A. , Fournier R. P. , Savoie R.
Published: May 2006

The Raman and infrared spectra of liquid and crystalline SiF4 have been recorded. The assignment of some of the Raman bands of the crystal to longitudinal modes has been confirmed by the infrared reflection spectrum. These indicate that the crystal structure is not centrosymmetric. In other respects the spectra are also more complicated than is expected on the basis of the previously reported Td3 structure. Possible explanations are discussed.
The critical constants and orthobaric densities of acetone, chloroform, benzene, and carbon tetrachloride
Authors: Campbell A. N. , Chatterjee R. M.
Published: May 2006

not available
Metal ion initiated halogenation reaction of N-haloamines
Authors: Minisci F. , Gardini G. P. , Bertini F.
Published: May 2006

The metal ion catalyzed chlorination of 1-chlorobutane, 1-chlorohexane, methyl-pentanoate, and methyl-heptanoate by protonated N-chloroamines proceeds by a free radical chain mechanism and the chain carrying species was shown not to be a chlorine atom, but an amino radical cation.
Mass spectra of labelled methylquinolines
Authors: Draper P. M. , MacLean D. B.
Published: May 2006

The mass spectra of some labelled methylquinolines have been studied. Randomization of all nine hydrogens in the molecule appears to precede hydrogen loss in the fragmentation of the monomethylquinolines and the formation of ring expanded intermediates is proposed to account for the randomization. Possible mechanisms for the ring expansion are considered.
Absolute rate constants for hydrocarbon autoxidation. XVIII. Oxidation of some acyclic ethers
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

Propagation and termination rate constants have been measured for autoxidation of benzyl phenyl ether, benzyl-t-butyl ether, isopropyl ether, and benzyl ether. In the case of isopropyl ether and benzyl ether, estimates have been made of inter- and intramolecular propagation rate constants. Reactivities of acyclic ethers towards the t-butylperoxy radical have been determined. Rate constants for autoxidation of cyclic and acylic ethers have been summarized and compared.
Composition and stability of some bivalent transition metal complexes of 3,5-dinitrosalicylic acid
Authors: Dube S. S. , Dhindsa S. S.
Published: May 2006

The interaction of Zn2+, Mn2+, Hg2+, and Cd2+ ions with 3,5-dinitrosalicylic acid was investigated by potentiometric titrations in aqueous 0.1 M KNO3 medium. In all cases the formation of 1:1 complex was indicated. The stability constants in the pH ranges 4.5–8.0, 4.5–8.0, 5.0–8.0, and 5.5–8.0 were determined by applying the Calvin and Melchior's extension of Bjerrum's method and the log K values were found to be 3.70, 2.95, 3.20, and 2.85, respectively. A comparative study of the complexes of 3,5-dinitrosalicylic acid with other bivalent metal ions has also been incorporated. The stability constants of the transition metal complexes obey the order Cu > Ni > Co > Zn > Mn, in agreement with Irving and William's rule.
Influence of inert gases on the catalytic oxidation of SO2
Authors: Yeramian A. A. , Silveston P. L. , Hudgins R. R.
Published: May 2006

A study was made of the influence of diluent gases on the reaction rate and activation energy of the oxidation of sulfur dioxide over vanadium pentoxide catalyst, an effect noted by Baron, Manning, and Johnstone in 1952. Results confirmed the occurrence of the effect in a still lower temperature range (350–470 °C). Using non-adsorbing gases, helium and argon, the effect was demonstrated to be free from chemisorption of the diluents.Data on activation energy vs. molecular weight of the gas phase, using helium and argon, were in qualitative agreement with predictions based on a momentum-exchange model of Baron etal. However, comparison of rates obtained with argon (monatomic) and nitrogen (diatomic) as diluents, combined with independent study of the rate controlling steps, casts doubt on the adequacy of the explanation offered by Baron etal.
Photosensitization by Cd 3P1 atoms. I. Decomposition of acetone
Authors: Kalra B. L. , Knight A. R.
Published: May 2006

The photodecomposition of acetone vapor at 255 °C sensitized by Cd 3P1 atoms has been investigated. On irradiation of the Cd–acetone system at 3261 Å, both direct and sensitized reaction occur. CO and CH4 are the only significant volatile products, and their yield is decreased by addition of SF6 as inert quenching gas. The required participation of triplet acetone molecules in the sensitized reaction and the virtual identity of the direct and sensitized decompositions provide additional evidence for the importance of this excited species in direct photolysis.
Etude quantitative des réactions d'ozonolyse. XIII. Sur la structure du zwitterion de Criegee
Authors: Klutsch G. , Grignon J. , Renard J. , Fliszár S.
Published: May 2006

The hydroxyperoxides R2CH(OOR1)OH (R1 = CH3, C2H5; R2 = CH3, i-C3H7) and their isomeric alkoxyhydroperoxides R2CH(OOH)OR1 can be differentiated by their polarographic behavior. These hydroxyperoxides are not produced in the ozonolysis of trans 4-methyl-2-pentene in the presence of methanol or ethanol. It is concluded that the zwitterionic [Formula: see text] structure does not participate in the mechanism of ozonide formation.
Nuclear recoil reactions in organomanganese compounds. IV. Fulvalenehexacarbonyldimanganese
Authors: DeJong I. G. , Wiles D. R.
Published: May 2006

The chemical effects of neutron capture have been studied in fulvalenehexacarbonyldimanganese, in order to determine whether or not the ring–ring bond survives nuclear recoil. Retention in the parent form (9.1 %) is comparable to that in other organomanganese compounds, while the radiochemical yield of CpMn(CO)3, the "monomer", is very much lower (0.2%). This suggests that the inter-ring bond is not broken under the conditions in the reaction zone. The formation of radiomanganese compounds with several carbonyl ligands (4.7%) is in accord with mass spectrometric evidence, which suggests that CO may be readily available in the reaction zone.
Basicities in the naphthyl azoxy series
Authors: Dolenko A. , Mahendran K. , Buncel E.
Published: May 2006

The pKa values of the conjugate acids of the six known phenyl–naphthyl and naphthyl–naphthyl azoxy derivatives have been measured by spectrophotometric methods in sulfuric acid solutions. Trends within the series are discussed in terms of derealization and structural effects. The azoxy bases deviate slightly from Hammett base behavior.
Application of the Hammett equation to non-aromatic unsaturated systems. VIII Ionization potentials
Authors: Charton Marvin
Published: May 2006

Ionization potentials of substituted ethylenes, trans-1-substituted propenes, and several sets of substituted carbonyl derivatives have been correlated with the extended Hammett equation. The electrical effect in the case of the ethylenes and propenes is characterized by a value of ε ≈ 2.0, whereas the carbonyl derivatives show values of ε in the range 0 to 0.4. This difference in the composition of the electrical effect is ascribed to loss of a π electron from the ethylenes and propenes and of an n electron from the carbonyl derivatives. For purposes of comparison, several sets of ionization potentials of substituted benzenes were also correlated with the extended Hammett equation. Values of ε ranged from 1 to 3; thus the substituted benzenes are comparable in their behavior to the ethylenes and propenes.
Determination of for aliphatic ketones from nuclear magnetic resonance chemical shift data
Authors: Lee Donald G.
Published: May 2006

The [Formula: see text] values for 3-pentanone, 2-butanone, and 3-methyl-2-butanone have been determined from chemical shift data. The values (−7.6, −7.1, and −7.2, respectively) are in good agreement with those previously determined for aliphatic ketones by use of ultraviolet–visible and Raman spectroscopy.
Transition state analysis. I. Correlation between solvent stretching frequencies and C vs. O product ratios in alkylation of ambient anions. A new explanation for the observed product ratios
Authors: Wigfield Donald C.
Published: May 2006

A new explanation is presented for the O to C product ratios observed in alkylation reactions of ethyl acetoacetate and related enolic and phenolic compounds, based on a Hammond postulate analysis of the nature of the transition states involved. The explanation not only covers the effects of solvent and the nature of the metal cation, but also encompasses the previously unexplained effect of the alkyl halide structure. From the latter effect, ground state interaction between solvent and alkyl halide is predicted. Evidence consistent with this interaction is found in linear free energy relationships between the ΔΔG‡ (C vs. O) values for various alkyl halides and the stretching frequency of the solvent (S=O of DMSO; P=O of HMPA) when measured as alkyl halide solutions.
Gallium and indium electrode potentials in fused LiCl–KCl eutectic
Authors: Shafir Joseph M. , Plambeck James A.
Published: May 2006

Electrode potentials of indium and gallium couples have been measured in dilute solutions of the ionic species in fused LiCl–KCl eutectic at 450 °C. Standard molar electrode potentials of the observed couples are −1.210, −0.944, and −1.136 V against a standard molar platinum reference for the In(I)–In(0), In(III)–In(I), and Ga(III)–Ga(0) couples, respectively. These oxidation states and potentials are compared with previous work in this and other fused salt systems.
Anharmonicity, solvent effects, and hydrogen bonding: NH stretching vibrations
Authors: Foldes A. , Sandorfy C.
Published: May 2006

The influence of solvent effects and hydrogen bond formation on the anharmonicity of the NH stretching vibration of simple secondary amides, lactams, anilides, indole, pyrrole, and imidazole have been studied; and the frequencies of the first and second overtones, their half widths and solvent shifts measured. The validity of Buckingham's theory is established in the case of inert solvents; whereas the second order perturbation treatments are shown to be inapplicable to the case of hydrogen bonding solvents. All NH stretching modes seem to exhibit the same anharmonic behavior which is very different from that of OH vibrations.
New chemical synthesis of 5′-phosphoribosyl-N-formylglycineamide
Authors: Chu Samuel Y. , Henderson J. Frank
Published: May 2006

A new and convenient synthetic route to formylglycineamide ribonucleotide, an intermediate in the pathway of purine ribonucleotide biosynthesis de novo, is described. The method utilizes direct phosphorylation of the 5′-position of the linear riboside without protection of the 2′,3′-hydroxyl groups of the ribose, and gives a good yield of mixed α and β anomers. This route is suitable for synthesis of the natural product in quantities required for biological studies.
Preparation of cis- and trans-2,5-dimethoxytetrahydropyran and cis- and trans-2,5-dimethoxy-6-methyltetrahydropyran
Authors: Srivastava R. M. , Brown R. K.
Published: May 2006

Hydroboration and subsequent oxidation of 2-methoxy-3,4-dihydro-2H-pyran gave a 1:2 mixture of cis- and trans-5-hydroxy-2-methoxytetrahydropyran (2). From the methylated product 4, trans-2,5-dimethoxytetrahydropyran could be obtained by gas–liquid chromatography. The cis-2,5-dimethoxy-tetrahydropyran (8) was obtained by conversion of 4 to 3-methoxy-3,4-dihydro-2H-pyran (6) which upon bromomethoxylation and subsequent reduction with palladium catalyst gave 8.Both cis- and trans-2,5-dimethoxy-6-methyltetrahydropyran (11) were obtained by hydroboration and oxidation of 2-methoxy-6-methyl-3,4-dihydro-2H-pyran (9) followed by methylation of the resulting product.
Réactions dans le sulfolane. VI. Etude de solutions des acides perchlonque, fluorosulfurique, pyrosulfurique et hexachloroantimonique
Authors: Benoit R. L. , Buisson C. , Choux G.
Published: May 2006

Nuclear magnetic resonance and certain conductivity data are reported for solutions of perchloric and fluorosulfuric acids in sulfolane. Additional measurements were made on solutions of disulfuric and hexachloroantimony (V) acids. HSbCl6 is a strong acid in this weakly basic dipolar aprotic solvent. HClO4, HSO3F, and H2S2O7 are incompletely dissociated with K = 10−2.7, 10−3.3, and ~ 10−5, respectively. The acid strength in dilute solution in sulfolane follows the order HClO4 > HSO3F > H2S2O7, which differs from that known in H2SO4 which is a strongly associated polar protic solvent.
γ-Radiolysis of hydrocarbons using perfluorocyclohexane as an electron scavenger: determination of the free ion yields
Authors: Sagert N. H. , Reid J. A.
Published: May 2006

The room temperature, liquid phase radiolysis of n-hexane, 3-methylpentane, and 2,2,4-trimethyl-pentane has been examined using perfluorocyclohexane as an electron scavenger. Yields of C6F11H and C6F11CH3 were determined for scavenger concentrations below 5 × 10−3 M, and from these results free ion yields of 0.08, 0.17, and 0.37 G units were deduced for n-hexane, 3-methylpentane, and 2,2,4-trimethylpentane, respectively. These results are in good agreement with those obtained by other methods.
Studies of specifically fluorinated carbohydrates. Part VII. Furanosyl fluorides derived from the D-xylo-hexofuranose system
Authors: Hall L. D. , Steiner P. R.
Published: May 2006

The 1H and 19F nuclear magnetic resonance spectra of several hexofuranosyl fluoride derivatives have been analyzed, using a combination of heteronuclear-decoupling and computer-analysis techniques. A long-range coupling of 4.8–6.3 Hz occurs between F1 and H4, whereas a very small coupling occurs between the similarly oriented F1 and H3 nuclei.
Fluorescence of chloropentafluoroacetone
Authors: Samant H. S. , Yarwood A. J.
Published: May 2006

The fluorescence of chloropentafluoroacetone in the gaseous state at room temperature is reported. The fluorescence extends from 337 nm to greater than 560 nm with a maximum intensity at 420 nm and is unaffected by low pressures of oxygen. The energy of the first excited singlet state is estimated as about 83 kcal and the fluorescence data for 313 and "290" nm excitation indicate that fluorescence enhancement occurs as the pressure increases. The fluorescent yield at high pressures [Formula: see text] is independent of the nature of the gas used to attain the high pressure. The lifetime of the fluorescent state is 35.1 ± 0.3 ns.A simple mechanism correlates the experimental observations and the values of the rate constants are considered. The reciprocal of the natural radiative lifetime is calculated to be 6.6 × 105 s−1 and the rate constant assigned to intersystem crossing to the triplet is 2.8 × 107 s−1. A comparison with the data in the literature for hexafluoroacetone shows the effect of substitution by a heavy atom in the fluorinated ketone. It about doubles the value of the rate constant associated with intersystem crossing from the first excited singlet state in the gas phase.
The decomposition of aqueous dithionite III. Stabilization of dithionite by cations
Authors: Lem W. J. , Wayman M.
Published: May 2006

At the same conditions of pH (3.5 to 5.0), temperature (23 °C), and concentration (1 to 10 × 10−3 M), ZnS2O4 is more stable in aqueous solution than Na2S2O4, and the rate of decomposition is much less sensitive to [H+]. At pH 4.5 and 5.0, the decomposition of the Zn salt is essentially linear, whereas the Na2S2O4 decomposes slowly at first, during an induction period, and then rapidly by an autocatalytic reaction. The rate of decomposition of dilute aqueous Na2S2O4 at pH about 4 is slowed greatly by the addition of small quantities of In3+, Cd2+, or Zn2+. The effect of the stabilizing ions is attributed to anti-catalytic action.
Free radicals in γ-irradiated disodium succinate. Part 2. Triclinic crystals
Authors: Fujimoto M. , Seddon W. A.
Published: May 2006

Electron spin resonance (e.s.r.) spectra and radiation processes in γ-irradiated triclinic crystals of disodium succinate are more complex than those observed in monoclinic crystals. At 77°K, three species coexist, −O2CCH2CH2ĊO22− (1), a distorted conformation of the radical −O2C(ĊHCH2)*CO2−(2), and an unidentified radical X. On warming to room temperature, 1 and X disappear, while 2 changes to a more stable conformation −O2CĊHCH2CO2− (3). In addition the species CO2− (4), and −O2CĊHCH3 (5) are produced. On further warming to 40 °C, species 4 disappears while at the same time species 3 increases in intensity. Radical 5 remains unaffected. Possible mechanism and comparisons with monoclinic crystals are discussed.
Proton spin – lattice relaxation time of aniline-d2 in deuterated benzene and deuterated aniline solution
Authors: Bock E. , Czubryt J. , Tomchuk E.
Published: May 2006

The proton spin – lattice relaxation time of aniline-d2 in deuterated aniline solution was determined as a function of concentration and temperature over the temperature interval 260–360 °K using a pulsed nuclear magnetic resonance technique. In addition the proton spin – lattice relaxation time of aniline-d2 in deuterated benzene solution at 20 °C was also determined. It was found that the activation energies of the intra- and inter-molecular relaxation rates were of similar magnitude, viz. 4.5 and 4.4 kcal/mole, respectively. It was also found that at 20 °C the rotational correlation time, τr, of the C6H5NH2 molecule in infinitely dilute perdeutero benzene solution was approximately half that of the partially deuterated aniline molecule, viz. 3.0 × 10−12 and 6.3 × 10−12 s, respectively, and that τr of C6H5ND2 in infinitely dilute perdeutero aniline solution is much larger than in infinitely dilute perdeutero benzene solution and is equal to 19 × 10−12 s.
Solubility of alkali metal and ammonium thiocyanates and iodides in tri-n-butyl phosphate
Authors: Hála J. , Tuck D. G.
Published: May 2006

The solubilities of lithium, sodium, potassium, caesium, and ammonium thiocyanates and iodides, and of rubidium thiocyanate, in tri-n-butyl phosphate (TBP), have been measured. In general, the solubilities decrease with increasing cation size, but the values for the ammonium salts are anomalously high. This is shown to be due to hydrogen-bonding between NH4+ and the phosphoryl oxygen of the solvent. The results are compared with those reported for other alkali metal salts in TBP.
Vibrational energy distribution in HF formed by elimination from activated CH3CF3 and CH2CF2
Authors: Clough P. N. , Polanyi J. C. , Taguchi R. T.
Published: May 2006

The combination–elimination reaction CH3 + CF3 → CH3CF3† → CH2CF2 + HF has been studied in a fast-flow system. Infrared chemiluminescence arising from the HF product has been observed from vibrational levels v = 1–4, and relative rate constants, k(v), have been obtained for HF formation in these levels. A study has also been made of the reaction CH2CF2 + Hg*(63P1) → CHCF + HF + Hg(61S0), which has been found to produce vibrationally-excited HF. Relative rate constants k(v) for vibrational levels v = 1–4 have been obtained. It appears that channelling of the potential energy into HF vibration, in the course of the elimination step, is more efficient in the first than in the second of these reactions. In the second reaction HF is eliminated with considerable rotational excitation.
The single crystal Raman spectrum of orthorhombic PbCl2
Authors: Ozin G. A.
Published: May 2006

The frequencies and symmetries of the even parity lattice vibrations of orthorhombic lead dichloride are determined by means of polarized Raman scattering from an oriented single crystal. The frequencies of the vibrations are interpreted in terms of symmetry co-ordinates and by comparison with the modes of the isomorphous lead dibromide.
Molar polarizations of the constituents in a molecular complex system
Authors: Chan R. K. , Liao S. C.
Published: May 2006

A method of evaluating the molar polarizations of the constituents and the dipole moment of the complex simultaneously in a quaternary molecular complex system of [Formula: see text] in an inert solvent, S, is proposed on the basis of an empirical relationship between the specific polarization of the solution and the weight fraction of molecule A in combination with the mass action law and the mixture law of specific polarization. The validity of the method is tested by using the data obtained in Smith's papers for the systems of aniline in dioxane–benzene, n-butyl alcohol in pyridine–benzene, and pyridine in n-butyl alcohol – benzene. The agreement in dipole moment of the complex between the proposed and Smith methods for the first two systems verifies the applicability of the proposed method, which also gives consistent results for the second and third systems, while no value for the third system is given in Smith's paper.
The photo-electron spectrum of XeF2
Authors: Brehm Burkhard , Menzinger Michael , Zorn Christian
Published: May 2006

Six electronic states of XeF2+ have been found in the photo-electron spectrum of XeF2• The adiabatic ionization potentials, vertical ionization potentials, and relative ionization probabilities for these states are compared with theoretical predictions and an attempt is made to assign the states in terms of molecular orbitals.
Conformational equilibria in some cyclic imines: NH and CH stretching vibrations and the axial lone pair
Authors: Krueger P. J. , Jan J.
Published: May 2006

The fundamental NH and CH stretching vibrations of a number of cyclic imines have been examined in dilute CC14 solution. A trans orientation of the N lone pair orbital and one or more hydrogen atoms on adjacent carbons lowers the relevant vCH ("Bohlmann" bands) and raises vNH reflecting an increase in the s-character of the CH bond(s), consistent with a partial delocalization of the lone pair electrons into the CN bond. Conformations in which this interaction occurs are thermodynamically favored, and the ΔH values for the lone pair axial–equatorial equilibrium in piperidine, pyrrolidine, and indolene are estimated to be 0.4, 0.2, and 0.1 kcal/mole, respectively, in dilute CCl4 solution.The effects of hetero ring size, N-substitution, α-methyl substitution, and the solvent environment are investigated.
Liquid phase photolysis of cyclobutanone
Authors: Klemm R. F.
Published: May 2006

The photolysis of cyclobutanone has been examined at 3260, 3130, and 2537 Å in a variety of solvents and as a pure liquid. Both decarbonylation and photocleavage to C2H4 and CH2CO occur with substantial yield in a manner which appears to be somewhat at variance with the currently accepted gas phase mechanism. While C2H4/(cyclopropane + propylene) is relatively insensitive to photon energy, there is a significant wavelength dependence in the rate of propylene formation suggesting that the photoreactions of cyclobutanone occur at rates comparable with relaxation times in solution.
Kinetics and mechanism of electrophilic bromination of acetylenes
Authors: Pincock James A. , Yates Keith
Published: May 2006

The rates of addition of molecular bromine in acetic acid to a number of acetylenes have been found to follow the general equation[Formula: see text]In the absence of bromide ion and at low bromine concentrations (< 2 × 10−4 M), only the k2 process is observable. These k2 values for a series of ring-substituted phenylacetylenes are correlated well with σ+ values and give a ρ value of −5.17 which is interpreted in terms of a transition state leading to a vinyl cation intermediate. As expected from this intermediate, both cis and trans dibromide products are formed and the bromoacetates are only of the Markownikoff type (1-acetoxy-1-phenylethylene derivatives). An ion pair scheme has been presented to account for the variation in product composition with substrate structure.In contrast to these results for phenylacetylenes, a cyclic bromonium ion intermediate is postulated for alkyl acetylenes on the basis of only trans dibromide formation for 3-hexyne and 1-hexyne.The kBr− values have also been obtained for the ring-substituted phenylacetylenes as well as 3-hexyne. For all the substrates studied, this kBr− process represents a bromide ion catalyzed attack of molecular bromine in an AdE3 mechanism. Thus only trans dibromide products are formed from this rate process. The non-linear σ+ plot for these values has been interpreted in terms of change in transition state structure with substituent.
σ- and π-Bonding capabilities of , , and in molybdenum hexacarbonyl derivatives
Authors: Barbeau C. , Turcotte J.
Published: May 2006

cis- and trans-[Formula: see text] and cis- and trans-[Formula: see text] have been prepared. The dipole moments of Mo(CO)5L, cis-Mo(CO)4L2, and cis-Mo(CO)3L3[Formula: see text] as well as those of cis- and trans-[Formula: see text] have been measured.As the infrared data for stretching as well as deformation vibrations do not clearly explain the differences in stability, ease of substitution, or dipole moments with the different ligands, we have used the model of variable donor–acceptor ability of ligands combined with the model of non-retention of charges on the metal to show the importance of steric hindrance in substituted metal carbonyls. It is also possible to differentiate the σ and π bonding capabilities of the ligands [Formula: see text], [Formula: see text], [Formula: see text]. It is shown that [Formula: see text] is a better donor or acceptor than [Formula: see text] or [Formula: see text].
Cyclononatrienes vs. dihydroanthracenes
Authors: Fraser Robert R. , Juraydini Adel
Published: May 2006

This paper provides evidence that three compounds previously assumed to be methoxyl derivatives of dihydroanthracenes (1) are actually cyclononatriene derivatives. The revised structural assignments, made on the basis of mass spectral and n.m.r. evidence, remove a previous inconsistency in their n.m.r. properties. The constancy of geminal coupling constants in all three cyclononatrienes is discussed.
Recoil reactions in neutron-activated nickel carbonyl
Authors: Wheeler O. H. , Trabal J. E. , Wiles D. R.
Published: May 2006

Retention of 65Ni in neutron-irradiated Ni(CO)4 has been measured both in the pure form and in n-heptane and Fe(CO)5 solutions, and mixed with triphenylphosphine [Formula: see text] in n-heptane solution. Retention was found to be nearly 100% in all cases except with high concentrations of Fe(CO)5, where the retention dropped off strongly. It is concluded that the high retention is the result of rapid exchange of CO with inactive Ni(CO)4. The effect of Fe(CO)5 is considered to be a hot-zone reaction. The presence of triphenylphosphinenickel tricarbonyl was found not to affect the retention in Ni(CO)4. This is taken to show that the 65Ni atoms formed in crystalline [Formula: see text] remain trapped in the lattice.
Concerning rhenium nitrogen fluoride and technetium nitrogen fluoride
Authors: Cowie M. , Lock C. J. L. , Ozog J.
Published: May 2006

We have shown that the reported (1) X-ray powder pattern of "ReNF" is that of NH4ReO4 and we suggest that the X-ray powder pattern of "TcNF" is that of (NH4)2TcF6. In light of these results we suggest that the existence of the discrete phases ReNF and TcNF has not been proven.
The nature of the coordination bond in metal complexes of substituted pyridine derivatives. V. 4-Methylpyridine complexes of Zn(II), Cd(II), and Hg(II)
Authors: Sears M. C. , Brooks W. V. F. , Brewer D. G.
Published: May 2006

In this paper, an attempt is made to interpret the π-bonding between a 4-methylpyridine ligand and the divalent ions of zinc, cadmium, and mercury, using the previously introduced Rπ parameter. To do this, the ν12 mode in the complexes is assigned and confirmed by a normal coordinate analysis based on a valence force field model.
Reactions of sodium N,N-diethyldithiocarbamate with some organic solvents
Authors: Heckley P. R. , Holah D. G. , Hughes A. N. , Leh F.
Published: May 2006

Sodium N,N-diethyldithiocarbamate reacts smoothly with methylene chloride (even in the presence of various transition metal ions) to give the dithiocarbamate ester Et2NC(S)SCH2S(S)CNEt2 in very high yield. With chloroform and acetonitrile, proton abstraction occurs followed by partial decomposition of the N,N-diethyldithiocarbamic acid so formed to give diethylammonium N,N-diethyldithiocarbamate.
Halogen exchange in reactions of boron halides with o-(trifluoromethyl)-phenyltrimethyl derivatives of silicon and tin
Authors: Chivers T.
Published: May 2006

The reaction of boron trifluoride with o-CF3C6H4SnMe3 in carbon tetrachloride gives o-CF3C6H4BF2, which with aqueous potassium fluoride is converted to K[o-CF3C6,H4BF3]. Boron trichloride and o-CF3C6H4SnMe3 undergo halogen exchange to give, after hydrolysis, o-CCl3C6H4B(OH)2. Halogen exchange also occurs between boron trichloride and o-CF3C6H4Y (Y = H, SiMe3) to give boron trifluoride and o-CCl3C6H4Y. The long range HF and FF nuclear magnetic resonance (n.m.r.) coupling constants observed for o-CF3C6H4-derivatives are briefly discussed.
Applications of proton magnetic resonance to rotational isomerism in halotoluene derivatives. IV. α,α,2,4,6-Pentachlorotoluene in carbon disulfide, an exchanging ABC system
Authors: Gyulai Helen G. , Fuhr B. J. , Hutton H. M. , Schaefer T.
Published: May 2006

The p.m.r. of α,α,2,4,6-pentachlorotoluene in carbon disulfide solution displays hindered rotation about the sp2–sp3 carbon–carbon bond, causing broadening and collapse of the proton resonance spectrum. A full line-shape analysis using the computer program DNMR gives an activation energy of 14.2 ± 0.3 kcal/mole, a frequency factor of 11.9 ± 0.2, an enthalpy of activation of 13.7 ± 0.3 kcal/mole, and an entropy of activation of −4.4 ± 1 e.u. These data are compared with the activation parameters obtained in methylcyclohexane and toluene-d8 solutions from different line shapes.
Stereospecific synthesis of cis- and trans-2-(3,4,5-trimethoxyphenyl)-cyclopropylamines
Authors: Cooper Paul D.
Published: May 2006

The title compounds were synthesized as models for examining stereochemical requirements of the mescaline receptor. By analogy with indolic psychotomimetic drugs, the pseudo-indolic structure of the cis compound should endow it with greater psychotomimetic activity than the trans isomer might possess. A special synthetic sequence was obligatory for the preparation of the cis isomer because the usual intermediates were either unreactive or were epimerized during subsequent transformations. Observed differences in the i.r. and n.m.r. spectra of the key intermediates, cis- and trans-2-(3,4,5-trimethoxyphenyl)-cyclopropanecarboxylic acids, are due to electronic factors introduced secondary to the stereochemical fixation of the functional groups. It is suggested that this unavoidable electronic perturbation must be taken into account in future considerations of drug-receptor interaction.
Etude spectroscopique des dérivés du peroxyde d'hydrogène. IV. L'acide de Caro, H2SO5
Authors: Arnau José L. , Giguère Paul A.
Published: May 2006

The i.r. and laser Raman spectra of pure, crystalline Caro's acid, H2SO5, were measured for the first time between 4000 and 30 cm−1. Most of the fundamental vibrations of the molecule could be identified by comparison with those of the H2SO4, H2O2 and HSO5− species. In addition, a dozen or so of lattice modes were recorded. The O—O stretching frequency is slightly higher (886 cm−1) than in solid H2O2, contrary to expectation. The two hydroxyl groups are quite different, both chemically (Caro's acid is essentially monobasic) and spectroscopically. The ionizable OH group forms strong intermolecular hydrogen bonds, as in H2SO4. However, the non-ionizable O2H group is engaged mainly in intramolecular hydrogen bonding. The unit cell of the crystalline acid must contain more than two molecules.
Etude des mouvements de molécules linéaires en phase liquide par analyse du profil des bandes d'absorption infrarouge. I. Oxyde nitreux
Authors: Vincent-Geisse J. , Soussen-Jacob J. , Tai Nguyen-Tan , Descout D.
Published: May 2006

Measurements have been made of the width and profile of the three fundamental vibration bands and of some harmonics of the N2O molecule in solution in a large number of solvents. In the case of some non polar solvents the widths of the bands observed appear to be determined by rotational motions of the solute molecules; in other cases variations in the intermolecular potential cannot be neglected. The correlation functions and corresponding moments were then calculated; the values obtained are interpreted using the hypothesis that the width arises as a result of rotation and rotational diffusion movements of the molecule; they appear approximately in agreement with theory in the case of non polar solvents. In addition, we give an approximate value of the torque acting on the N2O molecule in liquid medium.
Nature of the Coordination Bond in Metal Complexes of Substituted Pyridine Derivatives. VI. Electronic Spectra of Some Complexes of Copper(II)
Authors: Tong Miss M. , Brewer D. G.
Published: May 2006

The electronic spectra of some substituted pyridine complexes of copper(II) have been studied. The effects of bonding on the spectroscopic data are discussed, and compared with the Rπ values determined from infrared measurements.
Nitrogen Bridged Osmium-Ruthenium Complexes
Authors: Elson Clive M. , Gulens J. , Page John A.
Published: May 2006

The formation of [(H2O)(NH3)4Ru—N2—Os(NH3)5]4+ by the reaction of cis-Ru(NH3)4(H2O)22+and Os(NH3)5N22+ has been studied over the range 15–45 °C. The reaction followed second order kinetics with kt = 1.2 × 10–1 M–1 s–1 at 25.0 °C and Ea = 16.8 ± 0.1 kcal/mole. Measurement of equilibrium concentrations gave Keq = 4 × 103 M−1 at 25.0 °C.The (4+) dimer was stable but removal of the excess cis-Ru(NH3)4(H2O)22+ reactant by oxidation at −0.10 V was followed by dimer decomposition. The breakup obeyed simple first order kinetics with kr = 2.9 × 10−5 s−1 at 25.0 °C.Oxidation of the (4+) dimer at + 0.10 V gave a stable (5+) dimer. Removal of the excess Os(NH3)5N22+ reactant at + 0.30 V was followed by decomposition of the (5+) dimer giving Os(NH3)5N22+ and RuIII(NH3)4X2. The decomposition again obeyed first order kinetics with k1 = 1.5 × 10−5 s−1 at 25.0 °C. The (5+) dimer has an intervalence–transfer absorption band at 755 nm and is characterized as [X(NH3)4RuIII—N2—OsII(NH3)5]5+.The studies were carried out in an aqueous H2SO4–K2SO4 electrolyte of pH 3.3, µ = 0.30.
Infrared Studies of Water in Crystalline Hydrates: LiI.3H2O
Authors: Brink George , Falk Michael
Published: May 2006

The infrared spectra of undeuterated and partially deuterated LiI.3H2O were recorded between 4000 and 1000 cm−1. The splitting of the fundamentals of isotopically dilute HDO indicates that the water molecules are distorted and form one strong, linear OH … I− hydrogen bond and one weak, non-linear hydrogen bond. The non-equivalence of the two hydrogens of the water molecule disagrees with the space group P63mc − C6υ4 for this hydrate, proposed on the basis of X-ray diffraction studies. It is concluded that the space group, including hydrogens, is one of lower symmetry, P63 − C66. The gradual broadening and convergence of the HDO fundamentals at increasing temperature is explained by increasing librational motion of the water molecules.
X-Ray Induced Polymerization of Gaseous Vinyl Chloride. Effect of Additives
Authors: Grossoleil Jacques , Herman Jan A.
Published: May 2006

The X-ray induced polymerization in the gas phase of pure vinyl chloride and of its mixtures with O2, NO, SF6, NH3, CH3NH2, H2O, HCl, and C2H2 were examined. About 75% of the polymerization proceeds via a radical mechanism. The experiments indicate that most of the additives are deactivating chain transfer agents. Gel permeation chromatography showed that the polymer is activated by X-ray absorption during the time it takes to fall to the bottom of the irradiation cell, and forms a branched polymer.
Proton Magnetic Resonance Studies of Ionic Solvation in Ion-Exchange Resins. Part II
Authors: Sharma H. D. , Subramanian N.
Published: May 2006

The proton magnetic resonance spectra of anion-exchange resin Dowex AG1 of various crosslinkages ranging from X1 to X10 in the F−, Cl−, Br−, I−, NO3−, and ClO4− forms have been recorded and the values of the molal chemical shift, δ0x−, are found to be −0.035, 0.026 (assumed), 0.035, 0.045, 0.037, and 0.058 p.p.m./mol, respectively, for the anions. These values are generally lower compared to those observed in corresponding aqueous solutions, indicating that ion-solvent interactions are similar in both the resin matrix and the aqueous solution but there is probably increased ion association in the resin phase. The effective hydration numbers have been deduced from the temperature dependence measurements of proton chemical shifts for the alkali-metal ions and for a few anions in various crosslinkages of Dowex AG 50W and Dowex AG1 resins. The values of the hydration number decrease as the crosslinkage increases for the alkali-metal ions. The decrease in the hydration number at high crosslinkage is attributed to ion association in the resin phase. The reversal of selectivity in K+/Cs+ system below X16 in the sulfonated resin is explained on the basis of decrease in the hydration of K+ form of resin compared to that of Cs+ form, consistent with the experimental observations. The electrostatic interactions between the counterion and fixed group and ions and solvent in the resin phase have been discussed in the light of the proposed models.
Oligoribonucleotide Synthesis. II. Preparation of 2′-O-tetrahydropyranyl Derivatives of Adenosine and Cytidine Necessary for Insertion in Stepwise Synthesis
Authors: Neilson Thomas , Werstiuk Eva S.
Published: May 2006

The syntheses of N6-benzoyl-2′-O-tetrahydropyranyladenosine (2) and N4-benzoyl-2′-O-tetrahydropyranylcytidine (11) and their corresponding 5′-O-p-methoxytrityl derivatives, 3 and 12 respectively, are described. Compounds 2, 3, 11, and 12 are the protected derivatives of adenosine and cytidine required for insertion into a new oligoribonucleotide synthesis. Compound 2 was prepared from the known 2′-O-tetrahydropyranyladenosine by perbenzoylation followed by de-O-benzoylation. Compound 11 is prepared from cytidine by the following sequence: orthoacetate protection of the 2′- and 3′-hydroxyls; benzoylation of the 5′- and N4-positions; orthoacetate ring opening provided a mixture of the 2′- and 3′-monoacetates from which the major, 3′-O-acetyl-N4,5′-O-dibenzoylcytidine (7) was isolated; dihydropyran treatment on the 2′-hydroxyl of 7 and subsequent selective deacylation studies were carried out. Specific de-O-acylation gave 11.
On the Existence of Five-Coordinate Titanium(IV) Acetylacetonates
Authors: Holloway C. E. , Sentek A. E.
Published: May 2006

Monomeric trialkoxy(acetylacetonato)titanium(IV) compounds postulated as five coordinate complexes, are shown to be mixtures of well-established four and six coordinate derivatives. A structure is suggested for the dimeric species.
Thermochemistry of Silver Bromate
Authors: Gedansky L. M. , Hepler L. G.
Published: May 2006

Calorimetric measurements of the heat of solution of AgBrO3(c) in NH3(aq) have been combined with earlier data on heats of solution of AgNO3(c) in water and in NH3(aq) to yield ΔH0 = 11.78 ± 0.11 kcal mol–1 for AgBrO3(c) = Ag+(aq) + BrO3−(aq). Combination of this value with ΔG0 = 5.83 kcal mol–1 from the solubility product gives ΔS0°= 19.96 cal deg–1 mol–1 for the standard entropy of solution of AgBrO3(c) at 298 °K.
Chalkogenides of the Transition Elements. VIII. An X-Ray and Neutron Diffraction Study of the Spinel CoNi2S4
Authors: Huang Chung-Hsi , Knop Osvald
Published: May 2006

The crystal structure of the spinel CoNi2S4 was refined from X-ray and neutron powder-diffractometer data. The lattice parameter at room temperature and the positional parameter of the sulfur atom were determined as 9.424(1) Å and 0.2591(3). The neutron intensities show clearly that CoNi2S4 is an inverse spinel, Ni[CoNi]S4.
Oxochloride Complexes of Rhenium
Authors: Guest A. , Lock C. J. L.
Published: May 2006

Attempts to prepare rhenium hexachloride by the method described by Colton (2) have been unsuccessful. The products of the reaction were always impure rhenium oxotetrachloride and rhenium pentachloride. A compound of rhenium(VI), ReOCl4OPCl3, is shown to have a structure analogous to that of rhenium(V) ions [ReOX4.L]− in which the ligands are in a pseudooctahedral arrangement with L trans to the oxo-group (3). Reactions of ReOCl4 and ReOCl4-OPCl3 with pyridine and 2,2′-dipyridyl are described, and a scheme is proposed for the reactions of the products. Two stable complexes of perrhenyl chloride with the above amines have been obtained.
Optical Activity of Symmetric Compounds in Chiral Media. I. Induced Circular Dichroism of Unbound Substrates
Authors: Hayward L. D. , Totty R. N.
Published: May 2006

In the presence of chiral environment compounds, C, optical rotation is induced in symmetric substrates, S, and may be detected as circular dichroism in the electronic spectra of the solutions. Thus the n − π* transitions of symmetric and racemic carbonyl compounds, and of symmetric nitro and azo compounds, become optically active when these S are dissolved in chiral hydrocarbons, ketones, or carbinols, or in solutions of these C in achiral solvents. The rotational strengths of the induced circular dichroism bands of S are solvent, temperature, and concentration dependent. Only limited correlation of the sign and magnitude of the induced bands with the stereochemistry of C and S is evident on the data so far accumulated. Halogenated achiral solvents enhance the intensity, and, in some cases reverse the sign of the induced bands.A new mechanism of asymmetric induction is proposed in which specific bonding of C with S is not prerequisite.
Charge Localization in the Mass Spectra of Substituted Phenylbutyrophenones
Authors: Lightner D. A. , Steinberg Frank S.
Published: May 2006

A study of the McLafferty rearrangement of substituted phenylbutyrophenones relative to butyrophenones and 1-(4-butyrophenyl)-2-ethanes shows a peculiar non-linear relationship with the type of substituent and the distance of the substituent from the reaction site.
Sensitized Photolysis of Octacyanomolybdate(IV)
Authors: Wilson R. D. , Sastri V. S. , Langford C. H.
Published: May 2006

The photochemical loss of cyanide from Mo(CN)84− is shown to be sensitized by common organic triplet donors naphthalene, phenanthrene, anthraquinone, and benzophenone, but not by biacetyl. This suggests that the reactive state may be 3B1, not the lower lying 3A2. The quantum yields for sensitized photolysis (near 0.25) are larger than for the direct reaction (near 0.15). This is unlike the behavior of Co(CN)63− where the similarity of the two yields leads to the conclusion that higher excited states are efficiently converted to "the lowest triplet".Naphthalene irradiated at 286 nm leads to a quantum yield of 0.4 which is, perhaps, associated with a new process involving sensitized production of a solvated electron.Thermal solvolysis rates in several media are also reported. The medium dependence of solvolysis is small.
The Reaction of Carbon Disulfide with Aziridine Complexes of Nickel(II)
Authors: McCormick B. Jack , Kaplan Roy I. , Stormer Benjamin P.
Published: May 2006

Carbon disulfide has been shown to undergo insertion reactions with [Ni(aziridine)4,6]2+ and [Ni(2-methylaziridine)4]2+. The diamagnetic products are formulated as planar dithiocarbamate complexes in which the heterocyclic ring remains intact. The complexes have properties which are atypical of all dithiocarbamate complexes heretofore reported, and infrared and optical spectral measurements suggest that the insertion products may be the first examples of N,S-bonded dithiocarbamate ligands. In methanol the products slowly rearrange to give S,S-bonded complexes in which the aziridine rings have been opened.
γ-Radiolysis of Cysteine-Cysteamine Disulfide in Aqueous Solution
Authors: Purdie J. W.
Published: May 2006

γ-Radiolysis of a mixed disulfide, cysteine-cysteamine disulfide, in unbuffered aqueous solution (0.3 mM) was investigated in the presence and absence of oxygen. The principal products were the thiols (cysteine and cysteamine), the corresponding sulfinic and sulfonic acids, the symmetrical disulfides (cystine and cystamine) and ammonia. Cystine and cystamine were formed in very high yields in deaerated solution; (G(CySSCy) ~ 15) but addition of oxygen reduced the yield sharply and it was inversely proportional to the oxygen concentration except at very low oxygen levels. In aerated solution G(CySSCy) = 0.8. These observations were attributed to a chain reaction which was suppressed by oxygen:[Formula: see text]In the case of proteins, it was concluded that although chain reactions between RS• radicals and protein disulfide bonds were possible, they should be inhibited by oxygen.
Applications of Proton Magnetic Resonance to Rotational Isomerism in Halotoluene Derivatives. V. α,α,α′,α′,2,3,5,6-Octachloro-p-xylene, Semiempirical Barrier Calculations
Authors: Barber B. H. , Schaefer T.
Published: May 2006

In toluene-d8 solution the p.m.r. spectrum of α,α,α′,α′,2,3,5,6-octachloro-p-xylene at temperatures below −25 °C consists of two sharp peaks corresponding to the two conformations in which the methine protons lie cis and trans to each other in the plane of the aromatic ring. The barrier to rotation of the dichloromethyl groups is derived from a line-shape analysis of the rate-dependent spectra using the computer program ABXFIT. The activation parameters are EA = 13.6 ± 0.4 kcal/mol, log A = 11.3 ± 0.3, ΔH‡ = 13.1 ± 0.4 kcal/mol, ΔS‡ = −7.3 ± 1.3 e.u., ΔG‡ = 15.4 kcal/mol at 286 °K. The quoted errors are standard errors from least squares fits. These parameters are compared to the extensive data known for α,α,2,4,6-pentachlorotoluene. A series of barrier calculations, based on modified Buckingham and on van der Waals potential energy functions, are discussed with reference to various halotoluenes.
Reaction of 9-Acetyl-2,3,4,4a-tetrahydrocarbazoles with Ozone: a Novel Oxidative Rearrangement
Authors: Mclean Stewart , Trotz U. O.
Published: May 2006

When 4a-ethyl-2,3,4,4a-tetrahydrocarbazole or its 4a-bromoethyl analog reacted with ozone, only a small amount of material that corresponded to the anticipated ozonolysis product was obtained, the principal reaction pathway leading to a 4a-substituted 1-acetoxytetrahydrocarbazolenine, the product of an oxidative rearrangement.