Walter Gordy

Electronegativities of the Elements

Electronegativity values derived from various methods are compared, and a complete electronegativity scale is arranged for all the elements. A chart is given which shows a systematic relation of electronegativity to the periodic system of the elements. A linear relationship is found between electronegativity and the work function of metals.

A Relation between Bond Force Constants, Bond Orders, Bond Lengths, and the Electronegativities of the Bonded Atoms

A relation of the form k=aN(xAxB/d2)34+b has been found to hold accurately for a large number of diatomic and simple polyatomic molecules in their ground states. (The average deviation of k calculated from k observed for seventy‐one cases is 1.84 percent.) Here k is the bond‐stretching force constant, d the bond length, N the bond order, and xA and xB are the electronegativities of the bonded atoms. If k is measured in dynes/cm×10−5 and d in Angstrom units, a and b have the values 1.67 and 0.30, respectively, for stable molecules exhibiting their normal covalencies, except those in which both bonded atoms have only one electron in the valence shell; for diatomic molecules of the alkali metals, Na2, NaK, etc., a and b are 1.180 and −0.013, respectively; for hydrides of elements having a single electron in the valence shell, 1.180 and 0.040, respectively; and for diatomic hydrides of elements having two to four electrons in the valence shell, 1.42 and 0.08, respectively. Numerous applications of the relatio...

Electron Spin Resonance of an Irradiated Single Crystal of Alanine: Second‐Order Effects in Free Radical Resonances

The electron spin resonance of single crystals of l‐ and d‐alanine has been observed at T=300°K and analyzed for different orientations of the crystal in the magnetic field and at several microwave frequencies ranging from 9 kMc/sec to 34 kMc/sec. The stable free radical produced by the irradiation is proved to be of the form CH3CHR, where R is a group which has no nuclei with detectable coupling. The hydrogens of the CH3 group of the radical are shown to have equivalent, isotropic coupling of 26 gauss each, essentially independent of the frequency of observation. This CH3 group coupling is interpreted as arising from s orbital spin density of the hydrogens, via hyperconjugation. The hydrogen of the CH group has both an isotropic, Fermi term, Af=20 gauss, arising from s orbital density on the hydrogen, and an anisotropic term Aμ=7 gauss arising from dipole‐dipole interaction of the proton moment with the electron spin density, ρC, on the carbon. Although the signs of Af and Aμ could not be learned, they a...

ELECTRON SPIN RESONANCE IN A GAMMA-IRRADIATED SINGLE CRYSTAL OF L-CYSTINE DIHYDROCHLORIDE

The electron spin resonance of a gamma‐irradiated single crystal of L‐cystine dihydrochloride, HOOC–CH–CH2–S–S–CH2–CH–COOH·2HCl,         –                             –        NH2                      NH2 has been measured at 9 kMc/sec and at 24 kMc/sec for various orientations of the crystal in the magnetic field. The resonance pattern was found to be a doublet, the spacing between the components of which is independent of the crystal orientation as well as of the strength of the static magnetic field. The spectroscopic splitting factor was found to be anisotropic with the principal values: gu=2.003, gv=2.025, and gw=2.053. A model of the free radical, HOOC–CH–CH2–S·,          –        NH2 in which the electron spin density is mainly concentrated in a nonbonding 3 p orbital of the sulfur atom, is proposed. The model accounts very well for the principal values of the g tensor as well as their directions relative to the atomic configuration. It also can give rise to the observed proton hyperfine structure.

Microwave Spectra and Molecular Structures of Fluoroform, Chloroform, and Methyl Chloroform

Sufficient isotopic combinations have been studied to make complete structural determinations of fluoroform and chloroform from microwave rotational spectra. The dimensions of CHF3 are dCH = 1.098A, dCF = 1.332A, and ∠FCF = 108°48′; those of CHCl3 are dCH = 1.073A, dCCl = 1.767A, and ∠ClCCl = 110°24′. Measurements were made on only the most abundant isotopic species of CH3CCl3. If the CCl3 configuration as in chloroform and the CH3 configuration as in methane are assumed, the CC distance in CH3CCl3 is found to be 1.55A.

Millimeter‐Wave Rotational Spectrum of HSSH and DSSD. I. Q Branches

The Q‐branch rotational lines of H2S2 have been measured in the frequency range 80–200 Gc/sec, those of D2S2, in the range from 60 to 220 Gc/sec. For HSSH, measurements were made on the torsional vibrational state υt = 1, and the S–S bond‐stretching vibrational state υs = 1 as well as on the ground state. The molecules are the most nearly accidentally symmetric tops of any so far reported. Wangs asymmetry parameter bp = (C − B) / (2A − B − C) for the ground vibrational state of H32S32SH is found to have the value bp = − 1.10 × 10−5; for H32S34SH, bp = − 1.07 × 10−5; for D32S32SD, bp = − 2.10 × 10−6. The asymmetry increases markedly with the torsional oscillation: for H32S32SH when υt = 1, bp = − 4.055 × 10−5; it decreases with the S–S stretching: for H32S32SH when υs = 1, bp = − 7.72 × 10−6. The molecule is found to have the nonplanar chain structure HSSH, with the structural parameters having the values: dSH = 1.327 A, dSS = 2.055 A, ∠HSS = 91.32°, and the dihedral angle η = 90°36′. The barrier to relat...

Methyl Alcohol. II. Molecular Structure

From the moments of inertia of six different isotopic species of methyl alcohol as obtained from the J=0→1 rotational lines a complete structural determination of methyl alcohol has been made. The structural parameters so obtained are the following : dOH=0.956±0.015 A, dCO=1.427±0.007 A, dCH=1.096 ±0.010 A, ∠HCH=109°2′±45′, ∠COH=108°52′±2°, and the distance of the oxygen atom from the symmetry axis of the CH3 group=0.083±0.005 A.

Dependence of Bond Order and of Bond Energy Upon Bond Length

A simple inverse square relation of the form, N=aR−2+b, (where N is the bond order, R is the bond length, and a and b are constants characteristic of any given pair of atoms) has been found to agree satisfactorily with the available values for bond orders. For CC bonds a and b are found to have the values 6.80 and −1.71, respectively; for CN they are 6.48 and −2.00; for CO they are 5.75 and −1.85. The available data on bond energies suggest a relation of the same form, E=lR−2+m, between bond energy E and bond length R, where l and m represent the characteristic constants of a given atomic pair.

ESR of Free Radicals Trapped in Inert Matrices at Low Temperature: CH3, SiH3, GeH3, and SnH3

The free radicals CH3, SiH3, GeH3, and SnH3 have been produced in a krypton matrix at 4.2°K by γ irradiation of the matrix containing dilute concentrations of CH4, SiH4, GeH4, and SnH4. The electron spin resonances indicate free or restricted rotation for all the radicals in the matrix. Observed anisotropies in g show that SiH3, GeH3, and SnH3execute restricted rotation about an axis perpendicular to the symmetry axis. From the observed values for the rotating radicals, the axially symmetric principal g values for the static radicals are derived as follows: for SiH3, g∥ = 2.003, g⊥ = 2.007; for GeH3, g∥ = 2.003, g⊥ = 2.017; for SnH3, g∥ = 2.003, g⊥ = 2.025. Hyperfine structure caused by 29Si is observed for SiH3 with isotropic coupling constant Af = 266 G and anisotropic coupling Aμ = 24 G. These couplings reveal 22% scharacter in the orbital of the unpaired electron, which indicates that the radical is nonplanar with bond angles of 110.6°. Probably GeH3 and SnH3 are also nonplanar. The magnitudes of the ...

Precision measurement of dipole moments and other spectral constants of normal and deuterated methyl fluoride and methyl cyanide

Abstract From high precision measurements of first- and second-order Stark effects on both ΔM = 0 and ΔM = ±1 transitions, the molecular dipole moments of normal and deuterated methyl fluoride and methyl cyanide have been obtained as follows: for CH3F, μ = 1.8572 ± 0.0010 D; for CD3F, μ = 1.8682 ± 0.0010 D; for CH3CN, μ = 3.913 ± 0.002 D; for CD3CN, μ = 3.919 ± 0.004. A remeasurement of zero-field lines yields more accurate values of the spectral constants for three of these. They are: for CH3F, B0 = 25 536.148 ± 0.005 Mc/sec, DJ = 60.4 ± 0.10 kc/sec, DJK = 439.26 ± 0.05 kc/sec; for CD3F, B0 = 20 449.854 ± 0.012 Mc/sec, DJ = 34.2±0.4 kc/sec, DJK = 221.7 ± 0.9 kc/sec; for CD3CN, B0 = 7858.117 ± 0.008 Mc/sec, DJ = 4.64 ± 0.06 kc/sec, DJK = 110.59 ± 0.10 kc/sec.