WorldCat Identities

HARVARD UNIV CAMBRIDGE MASS Dept. of CHEMISTRY

Overview
Works: 39 works in 39 publications in 1 language and 39 library holdings
Publication Timeline
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Most widely held works by HARVARD UNIV CAMBRIDGE MASS Dept. of CHEMISTRY
The boranes and their relatives : [Nobel lecture] by William N Lipscomb( Book )

1 edition published in 1977 in English and held by 1 WorldCat member library worldwide

An investigation of the reaction products of bis-cyclopentadienyltitanium dichloride and various aluminum alkyls by electron spin resonance( Book )

1 edition published in 1960 in English and held by 1 WorldCat member library worldwide

Bis-cyclopentadienyl titanium dichloride (I) was allowed to react with about a thousandfold excess of several aluminum alkyls in benzene solution and the electron spin resonance (e.s.r.) spectra of these solutions were observed at 3.2 cm. wave length and at 20C. The reactions with several aluminum alkyls were investigated: Me3Al, Et3Al, iso-Bu3Al, Et2AlCl, and EtAlCl2. The nature of the e.s.r. spectrum was found to depend upon the aluminum alkyl which was allowed to react with I. Furthermore, the e.s.r. spectrum of the EtAlCl2 system was found to change with time. The product of the reaction between Et3Al and I was shown to be the compound Cp2TiCl2AlEt2, which has one unpaired electron. The final products of the reactions based upon Et2AlCl and EtAlCl2 are most probably the compounds Cp2TiCl2AlEtCl and Cp2TiCl2AlCl2, respectively. The spectra indicate that more than one paramagnetic species is present. The compositions and structures of the products of systems based upon Me3Al and isoBu3Al are not known, but the formulations Cp2TiCl2AlR2 may well apply. (Extracted)
The oxidation of carbon monoxide/methane mixtures in shock waves( Book )

1 edition published in 1970 in English and held by 1 WorldCat member library worldwide

CO/O2/Ar mixtures with mole fractions of 4%/2%/94% and containing 180 or 500 ppm CH4 were investigated in incident shock waves at about 5 x 10 to the 17th particles/cc total concentration. The reaction was followed by measuring infrared emissions from CO2 and CO for about 1500 microsec particle time over the temperature range 1750 -2575K. The rate of CO2 production initially increased exponentially and then became constant after several percent conversion. It was possible to quantitatively describe the observations in terms of a mechanism. Methane was found to be more effective than either H2 or H2O in promoting the branching chain oxidation of CO. Extending these observations, it is shown that extremely small concentrations of organic compounds can strongly influence many features of the CO/O2 system. (Author)
Correlations between Wettability and Structure in Monolayers of Alkanethiols Adsorbed on Gold( Book )

1 edition published in 1988 in English and held by 1 WorldCat member library worldwide

Long-chain aklanethiols absorb onto gold from solution and from monolayers. Coadsorption of HS(CH2)11OH and HS(CH2)21CH3 from ethanolic solutions of varying composition generates monolayers, the wettability of which is correlated closely with the composition of the monolayer. Absorption of the longer chain thiol is preferred over the short chain, and formation of monolayers comprising predominantly one component is favored over mixed monolayers containing both component thiols
Resonances in the scattering of electrons from atoms( Book )

1 edition published in 1966 in English and held by 1 WorldCat member library worldwide

A formal procedure is developed for describing the resonances in electron-scattering from atoms caused by metastable, auto-ionizing states. It is shown that the position of a particular resonance is given exactly by the usual Rayleigh-Schrodinger perturbation series pertaining to an unperturbed discrete state embedded in an unperturbed continuum. An expression is given for the width which shows explicitly what initial state i and final state f should be used in the 'golden rule' as applied to autoionization. The formal results are applied to the lowest 1Pu resonance in He(+) - e( - ) scatering; i.e., the 2s2p 1Pu metastable state of He. The resonance energy obtained is 60.28 ev above the ground state of He, and the calculated width is 0.038 ev. These results are seen to be in excellent agreement with the experimental values. (Author)
THE MICROWAVE SPECTRUM OF PIVALALDEHYDE( Book )

1 edition published in 1966 in English and held by 1 WorldCat member library worldwide

The microwave spectrum of pivalaldehyde ((CH3)3CCHO) was investigated in the frequency region 9-40 kMc/sec. The ground state, first and second excited states of the t-butyl torsion, and the first excited state of each of the three methyl torsions were assigned. The barrier to internal rotation of the t-butyl top was calculated from the splittings in the first excited state to be 1186 cal/mole, from the splittings in the second excited state to be 1176 cal/mole, and from the intensities of the first excited state relative to the ground state to be 1100 cal/mole. The excited states of the methyl torsions show no splittings, but the relative intensities yield barrier estimates of 2600 cal/mole, 3500 cal/mole, and 3800 cal/mole, if one assumes that the three tops are independent. On the basis of certain analogies with previously investigated molecules the lowest of these barriers is very tentatively assigned to a methyl group which is eclipsed with respect to the oxygen atom. The dipole moment components were computed from Stark effect measurements to be mu-a = 2.56 D and mu-b = 0.76 D. (Author)
The oxidation of carbon monoxide by oxygen in shock waves( Book )

1 edition published in 1969 in English and held by 1 WorldCat member library worldwide

The oxidation of CO, with and without small amounts of added hydrogen, was investigated in very dilute mixtures with argon. The reaction was followed in incident shock waves by measuring CO and CO2 infrared emissions for about 2000 micro sec particle time over the 1700 to 2300K range. The reaction shows an initially increasing (exponentially in many runs) rate followed, under most conditions, by a period of constant rate. The observed CO2 concentration - time profiles were compared to those calculated numerically on a computer. These calculations used two mechanisms, proposed by others, for the shock tube oxidation of CO. The level of impurities in gases used was extensively investigated. Relation of the presently reported data to those of others is discussed. (Author)
The microwave spectrum, structure, dipole moment and quadrupole coupling constant of germyl cyanide( Book )

1 edition published in 1966 in English and held by 1 WorldCat member library worldwide

The symmetric top spectra of ten isotopic species of GeH3CN were observed and measured. From the rotational constants obtained the following structural parameters were derived: r(C-N) = 1.55 plus or minus 0.001 A and r(Ge-C) = 1.919 plus or minus 0.001 A, assuming r(Ge-H) = 1.529 A and a tetrahedral distribution about the Ge atom. From an analysis of the splittings observed in the 1 to 2 transitions of GeH3CN a quadrupole coupling constant for the nitrogen nucleus of -5.0 plus or minus 0.1 Mc/s was obtained. Analysis of the Stark effect gives a dipole moment of 3.99 plus or minus 0.05 D. (Author)
The Formation of Metallocycloimides from the Reaction of Isocyanates with a Neutral Transition Metal Carbonyl( Book )

1 edition published in 1986 in English and held by 1 WorldCat member library worldwide

The nucleophilic carbonyl complex (W(eta-C5H5)2(CO)) (1) reacts readily with the isocyanates OCNR (R = CH3, Ph) in pentane to give the first reported metallocycloimides (W(eta-C5H5)2(C(O)N(CH3)C(O))) (2) and (W(eta-C5H5)2(C(O)N(Ph)C(O))) (3). It is suggested that the reaction involves initial eta 1-C coordination of an isocyanate to give a zwitterionic intermediate in which the ligands are simultaneously activated in opposite senses, and that nucleophilic attack by the heteroallene on the electrophilic carbonyl then gives a metallocycloimide. Complex 2 has been structurally characterized by a single crystal X-ray diffraction study (monoclinic space group P2 sub 1/m, with Z = 2; a = 7.6586 A, b = 8.6718 A, c = 9.6557 A; Beta = 101.45 deg; d calc = 2.20 g/cc; R = 2.20 % and R sub w = 2.19 %) which establishes that the metallocycloimide group is essentially planar. Both 2 and 3 are moderately water sensitive, regenerating 1 at 55 C and ambient temperatures respectively. Complex 1 in toluene does not react with 1.7 atmospheres of CO2 at temperatures up to 85 C
Reductive Disproportionation of Carbon Dioxide by Dianionic Carbonylmetalates of the Transition Metals( Book )

1 edition published in 1986 in English and held by 1 WorldCat member library worldwide

Carbon dioxide reacts readily with M2(M'(CO)5) (M = Li, Na, K, M' = W; M = K, M' = Cr, Mo, W) to give the corresponding group 6 hexacarbonyls (M(CO)6) and alkali metal carbonates. The reaction of Li2(W(CO)5) with excess 13CO2 at -78 C gives (W(CO)5(13CO)), confirming that the reaction involves reductive disproportionation of CO2 to CO and CO3(2- ). The group 8 carbonylmetalates Na2(M(CO)4) (M = Fe, Ru, Os) react with CO2 to give (M(CO)5) and carbonate, and Na2(V(eta-C5H5)(CO)3) reacts with CO2 to give (V(eta-C5H5)(CO)4) and carbonate, indicating that reductive disproportionation is a general reaction of dianionic carbonylmetalates with CO2. Careful addition of one equivalent of CO2 to a solution of Li2(W(CO)5) at -78 C leads to an intermediate 1:1 adduct with an IR spectrum consistent with formulation as Li2(W(CO)5(eta 1-CO2)). The principal 13C absorption at 223.4 delta of a sample of Li2(W(CO)5(eta 1-13CO2)) prepared at -78 C exhibits Jw-c = 92 Hz, consistent with the central C being directly bonded to W and superscript 2 hybridized. Oxide scrambling from coordinated CO2 to coordinated CO at higher temperatures results in complex signals between 205 and 201 sigma assigned to the carbonyl ligands
Comparison of Self-Assembled Monolayers on Gold: Coadsorption of Thiols and Disulfides( Book )

1 edition published in 1989 in English and held by 1 WorldCat member library worldwide

Ordered, organic monolayers were formed on gold slides by adsorption from ethanol of HS(CH2)10CH2OH, HS(CH2)10CH3, S(CH2)10CH2OH2, S(CH2)10Ch32, and of binary mixtures of these molecules in which one component was terminated by a hydrophobic methyl group and one by a hydrophilic alcohol group. The compositions of the monolayers were determined by X-ray photoelectron spectroscopy (XPS). Wettability was used as a probe of the chemical composition and structure of the surface of the monolayer. When monolayers were formed in solutions containing mixtures of a thiol and a disulfide, adsorption of the thiol was strongly preferred (approx. 75:1). Monolayer, Gold, Surface, Contact angles, Thiols, Disulfides. (mjm)
Electron-spin resonance of electrochemically generated free radicals isomeric dinitrobenzene mononegative ions( Book )

1 edition published in 1960 in English and held by 1 WorldCat member library worldwide

The monomegative ions of meta-, ortho- and paradinitrobenzene were prepared in acetonitrile by controlled potential electrolysis within a microwave cavity and their electron spin resonance observed. The radical spectra exhibit hyperfine structure due to the isotropic magnetic interaction of the unpaired electron with the nitrogen and ring proton nuclear moments. Coupling constants were obtained with the aid of deuterium substitutions in the parent molecule. The nitrogen hyperfine coupling constants for the isomeric meta, ortho, and para anions were found to be 4.68, 3.22, and 1.74 gauss, respectively, and were identical for each of the two nitrogen nuclei of a given radical. Proton coupling constants range between 0.42 gauss and 4.19 gauss. The larger total hyperfine width of the metal-dinitrobenzene anion compared with the ortho and para isomers is ascribed to the existence of negative spin density in the pi system of the first-mentioned radical and to the possibility of quinonoid resonance in the others which places considerable unpaired, spin density in the oxygen nonbonding orbitals. (Author)
The microwave spectrum of xenon oxytetrafluoride( Book )

1 edition published in 1964 in English and held by 1 WorldCat member library worldwide

The microwave spectrum of XeOF4 was investigated in the region of 20-40 kMc with a conventional Stark modulated spectrometer. Transitions were observed for five naturally-occurring isotopes of xenon in the 016 species and for two of these isotopes in an 018 enriched sample. The simplicity of the spectrum and its first order Stark effect are characteristic of symmetric tops. From the rotational constants of the various isotopic species the structural parameters, based on a C4v model, were calculated. The xenon-oxygen bond appears to be a little shorter in XeOF4 than in crystalline XeO3 for which X-Ray methods give 1.76 A. This is consistent with the force constants measured for the two compounds: 7.10 md/A for XeOF4 and 5.66 md/A in XeO3. (Extracted)
Wetting of Functionalized Polyethylene Film Having Ionizable Organic Acids and Bases at the Polymer-Water Interface: Relations between Functional Group Polarity, Extent of Ionization, and Contact Angle with Water( Book )

1 edition published in 1988 in English and held by 1 WorldCat member library worldwide

This paper examines the wetting by water of low density polyethylene film modified at the polymer water (air) interface by introduction of polar organic functional groups (carboxylic acids, amines, and others). Water/polymer contact angles were determined for each of these interfaces; for interfaces containing acidic or basic functional groups, the contact angle was determined as a function of the pH. The observed contact angle was related to the hydrophilicity of these functional groups: as the hydrophilicity (as measured by Hansch pi parameters) increased up to a certain point, the contact angle decreased. Beyond that point, increased hydrophilicity had little additional influence on the contact angle. The result is interpreted in terms of water adsorbed on the polar interfacial functional groups: extensive hydration of interfacial groups having large negative pi parameters moderates their effective hydrophilicity. Keywords: Polyethylene, Wettability, Ionization, Acids, Bases, Monolayers, Gold
The oxidation and pyrolysis of ethylene in shock waves( Book )

1 edition published in 1967 in English and held by 1 WorldCat member library worldwide

The oxidation of C2H4 was studied in a shock tube by monitoring the infrared emissions from CO and CO2 and the visible emission from CH*. The characteristics of this oxidation closely resemble oxidations of C2H2 and C2H2 + H2. The induction periods and exponential time constants for the early phase of CO formation are the same for all three oxidations over the temperature range of 1500K to 2300K and lead to a common activation energy of 17 +1 or -1 kcal/mole. Above 1800K, the C2H4 - O2 reaction, in its early stages, consists mainly of the pyrolysis of C2H4, and the concurrent oxidation of pyrolysis products, C2H2 and H2. Later in the reaction, and more prominently so at lower temperatures, the reaction changes in character to a slower direct oxidation of C2H4. The relative rates of CO and CO2 production in both C2H4 - O2 and C2H2 - O2 reactions are reported as a function of temperature. The pyrolysis of C2H4 was also studied in the shock tube by an infrared technique and its rates determined between 1950K and 2250K. The results give an activation energy of 52 kcal/mole for the reaction. The oxidation results would indicate that C2H4, above 1800K, decomposes mainly by a molecular rather than a radical mechanism. (Author)
Electrochemical generation of free radicals and their study by electron spin resonance spectroscopy; the nitrobenzene anion radical( Book )

1 edition published in 1959 in English and held by 1 WorldCat member library worldwide

The nitrobenzene anion radical, (.C6H5NO2)( - ), was prepared by constant potential electrolysis of nitrobenzene solutions at a mercury pool electrode placed directly inside the microwave cavity of an electron spin resonance spectrometer. Acetonitrile was used as a solvent with tetra-n-propylammonium perchlorate as supporting electrolyte. Well-resolved electron spin resonance spectra of the radical reduction product exhibit a hyperfine structure consisting of fifty-four components. Hyperfine coupling constants were assigned for the interaction of the unpaired electron with the various ring protons and the nitrogen nucleus. The odd electron distribution in the molecule is seen to be at least qualitatively in agreement with that predicted by conventional valence bond theory. The large hyperfine interaction with the nitrogen nuclear moment is presumed to arise from a sigma-pi exchange interaction on the nitrogen atom. Electrochemical generation in acetonitrile offers advantages over conventional alkali metal reductions in solvents such as tetrahydrofuran and 1,2-dimethoxyethane. (Author)
Formation of Monolayers by the Coadsorption of Thiols on Gold: Variation in the Length of the Head Group, Tail Group, and Solvent( Book )

1 edition published in 1989 in English and held by 1 WorldCat member library worldwide

Long-chain alkanethiols, HS(CH2) (n)X, adsorb from solution onto gold and form oriented, ordered monolayers. Although alkyl chains terminated by other functional groups (e.g., trialkylphosphines, dialkyl disulfides and dialkyl sulfides) also form monolayers on gold that are stable at room temperature, thiols are adsorbed preferentially from solutions containing mixtures of a thiol and one of these other adsorbates. Surfaces containing more than one functional group can be generated by coadsorption of two or more thiols from solution. In general, the ratio of the concentrations of the two components in a mixed monolayer is not the same as in solution but reflects the relative solubilities of the components in solution and interactions between the tail groups, X, in the monolayer. Multi-component monolayers do not phase-segregate into single-component domains large enough to influence the contact angle (a few tens of angstroms across), but also do not act as ideal two-dimensional solutions. From dilute solutions in alkanes, adsorption of HS(CH2)10CH2OH is strongly preferred over HS(CH2)10CH3, probably due to the stabilization afforded by intra-monolayer hydrogen bonds between the hydroxyl tail groups. The wettability of mixed monolayers is not linear in the composition of the surface. In a surface comprising a polar and a nonpolar component, the polar component is more hydrophilic when its concentration in the monolayer is low than when the monolayer is composed largely of the polar component. (AW)
The Anthranilate Amide of 'Polyethylene Carboxylic Acid' Shows and Exceptionally Large Change with pH in Its Wettability by Water( Book )

1 edition published in 1988 in English and held by 1 WorldCat member library worldwide

The amide formed from polyethylene carboxylic acid (PE-CO2H) and anthranilic acid shows an exceptionally large change in wettability by water with pH. The values of advancing contact angles theta(a) are theta(a)(pH 1) = 110 degs and theta(a)(pH 12) = 33 degs. Comparison of these values with those for corresponding amides of meta- and para-aminobenzoic acid and aniline suggest that both conformational mobility of the polar functional group at the solid-water interface and surface roughness contribute to this large value. (AW)
Electron spin resonance study of p-phenylene-diamine positive ion( Book )

1 edition published in 1960 in English and held by 1 WorldCat member library worldwide

The mono-positive radical ion of p-phenylene diamine was prepared by controlled potential electrolysis and studied by electron spin resonance. This ion was formed in acetonitrile solution with sodium perchlorate as supporting electrolyte and the controlled potential electrolysis was carried out in the microwave cavity of the ESR spectrometer. The ion exhibits a complex hyperfine structure in dilute solution; the observed spectrum consists of about 75 hyperfine components. Isotropic hyperfine coupling constants were assigned for the three types of interacting nuclei: the aromatic ring protons, amine protons, and the nitrogen nuclei. The large nitrogen hyperfine interaction observed is in marked contrast to Wurster's Blue cation, for which this interaction is vanishingly small. ESR spectra of deuterated derivatives were obtained and employed in making the assignment. The magnitude of the nitrogen hyperfine interaction relative to that of the amine protons is shown to be consistent with the mechanism of pi-sigma electron exchange interaction on the nitrogen atom. Electrochemical generation allows the study of the relatively unstable ion-radical, whereas other methods of preparation have been less successful. (Author)
Monolayer Films Prepared by the Spontaneous Self-Assembly of Symmetrical and Unsymmetrical Dialkyl Sulfides from Solution Onto Gold Substrates: Structure, Properties, and Reactivity of Constituent Functional Groups( Book )

1 edition published in 1987 in English and held by 1 WorldCat member library worldwide

Exposure of evaporated gold films supported on silicon wafers to solutions of dialkyl sulfides (R(CH2)m-S-(CH2)n-R'; R and R'=CH3 or CO2H) or alkyl thiols (R(CH2)nSH, R=CO2H or CH3) in methanol or ethanol results in rapid formation of a monolayer of the organosulfer compound adsorbed onto the gold. The resulting films have been characterized using a number of techniques, including X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IRS), ellipsometry, and wetting. These self-assembled, supported organic monolayer films are systems that can be used to study problems in the physical-organic chemistry and materials science of organic surfaces, especially the relation between the molecular-level structure of the film constituents and the macroscopic properties of the assembled monolayers. Keywords: Thin film, Monolayer, Surface spectroscopy, electronic materials
 
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Audience level: 0.99 (from 0.98 for The borane ... to 0.99 for Electroche ...)

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English (20)