The Additivity of the Energies of Normal Covalent Bonds

The chemical bond between two identical atoms, as in the molecules H2, Cl2, etc., may be considered as an example of a normal covalent bond, involving an electron pair shared by the two atoms. The wave function representing this bond cannot necessarily be closely approximated by a function of the Heitler-London type, with the electrons staying on different atoms, but may contain ionic terms, corresponding to the two electrons of the bond on the same atom, the term representing the configuration A+A- occurring, of course, with the same coefficient as that for A -A +. The contribution of these ionic terms to the wave function for the normal state of the hydrogen molecule has been discussed by Slater [1]

The Iron Catalyzed Reaction between Nitrosyl Disulfonate and Hydroxylamine Monosulfonate Ions

Potassium nitrosyl disulfonate, K2NO(SO3)2, is noteworthy because the solid salt is orange in color and diamagnetic while its neutral aqueous solutions are purple in color and paramagnetic. These neutral solutions hydrolyze slowly to form N2O and hydroxylamine sulfonates; on the addition of acid the rate of hydrolysis is markedly increased. The mechanism of the hydrolytic reaction is unexpectedly complex as was found by Murib and Ritter [1] and, independently, by us. In order to obtain a more comprehensive picture of the mechanism of the hydrolytic reaction we have explored additional reactions which may play a part in the hydrolysis

The Kinetics of the Exchange of Tritium between Hypophosphorous Acid and Water

We have measured the rates of exchange of radioactive hydrogen (tritium) between tritiated water, HTO, and the thwo "undissociable" hydrogens of monobasic hydrophosphorous acid, H3PO2

The Raman Spectra and Molecular Constants of Phosphorus Trifluoride and Phosphine

The Raman frequencies of PF3(l) were found to be omega1(1), 890 cm^-1; omega2(1), 531 cm^-1; omega3(2), 840 cm^-1; and omega4(2), 486 cm^-1, indicating a regular pyramid structure of the molecule. Three frequencies were observed for PH3(l): 2306 cm^-1, 1115 cm^-1 and 979 cm^-1. With the aid of electron diffraction data the standard virtual entropies of PF3(g), PCl3(g), AsF3(g), and AsCl3(g) at 25°C are calculated to be 64.2, 74.7, 69.2, and 78.2 cal./deg., respectively; that of PH3(g) is estimated to be 50.5 cal./deg. These data lead to the following free energies of formation at 25°C: AsCl3(g), -62,075 cal.; PH3(g), 2750 cal.; PCl3(g), -62,220 cal

The Raman Spectrum of Arsenic Trifluoride and the Molecular Constants of AsF3, AsCl3 and PCl3

The Raman spectrum of AsF3 was found to consist of four lines with the frequencies omega1(1), 707; omega2(1), 341; omega3(2), 644; and omega4(2), 274 cm^—1. The selection rules require a pyramidal molecule. Electron diffraction data for AsF3, AsCl3 and PCl3 are used to establish the bond angles. The entropies of the three trihalides were calculated, and the standard free energies of formation of AsCl3(l) and AsCl3(g) were determined to be —65,190 cal. and —62,718 cal., respectively, at 25°

The Raman Spectra of CH3CF3 and CCl2CF2

Because of the interest attached to ethane and ethane-like molecules in connection with the question of free rotation of the CX3 groups with respect to each other, it was considered that the Raman spectrum of CH3CF3 might yield additional information on this point. Inasmuch as the spectrum of the liquid can be conveniently photographed only at low temperatures (b.p. about -40°), the determination of the polarization of the scattered light would be experimentally very difficult and was not attempted. The fact that the frequencies associated with the CF3 group will be considerably different in magnitude from those of the CH3 group may, in the analysis, compensate for the lack of data on polarization. Only the results of the experiments are presented here; the assignment of the frequencies will be given when completed. The Raman spectrum of the ethylene-like molecule CCl2=CF2 was photographed at room temperature with the substance in the liquid state, and the observed shifts are presented here

The Valence of Sulfur in Dithionates

It has been shown by Lindh [1] and others [2] that the shift in the K absorption edges for various compounds of sulfur, chlorine, phosphorous, iron, and some other substances, depends chiefly on the valence of the element in a given compound. With increasing valence in a given element the wave-length of the edge shifts to smaller values. Stelling [3] has explained the effect of valence as being due to the screening effect of electrons in external parts of atoms. To be sure, other factors influence the position of the edges, such as other elements occurring in the compounds, and lattice structure, but these factors produce in general only minor fluctuations around a mean value, whereas the mean values for the several valences show rather wide divergences. For example, the wave-lengths of the principal K edge of a large number of 4- and 6-valent inorganic sulfur compounds practically all lie within half an X-unit of the means of their respective groups, whereas the means themselves are separated by 8 X. U. A similar state of affairs is observed in the 2-valent compounds. The edges do not lie quite so close to the mean, but the mean is 13 X. U. from that of the 4-valent compounds. All the substances thus far investigated bear out the general statements above. In view of the rather large body of facts now before us, it seems legitimate to try to use x-ray absorption data to obtain information on the valence state of an element in a compound. The substance used in the present investigation was potassium dithionate, the object being to determine the state of the two sulfur atoms in K2S2O6. Lindh [4] has already shown that for Na2S2O3 and some other thiosulfates there is not just a simple absorption edge, but two edges, corresponding in position to the valence states SII and probably Siv, which states are generally assumed by chemists for the two sulfur atoms in the thiosulfates. Now if valence is calculated in the usual way, then on the assumption that the sulfur atoms of the dithionates are in the same state we get for them a valence of V, and we would expect to find the K absorption edge corresponding to a single state, rather than the two edges shown by the thiosulfates

The Raman Spectrum of Boron Trifluoride Gas

The Raman spectrum of BF3 was photographed using a purified preparation obtained from the thermal decomposition of C6H5N2BF4. Of the lines observed, that with the frequency 888 cm^—1 is certainly, and the band at 439–513 cm^—1 is probably due to BF3. The Raman frequencies and the infra-red results of Bailey et al. are assigned to the fundamental modes of vibrations

Chemical Identification of the Radioelements Produced from Carbon and Boron by Deuteron Bombardment

Chemical experiments were made on the radioactive substances resulting from the bombardment of carbon and boron by deuterons. Carbon is shown to yield an isotope of nitrogen and boron an isotope of carbon. The nitrogen so formed has a half-life of 10.5 minutes while that found by Curie and Joliot on bombardment of boron with alpha-particles has a half-life of 14 minutes. These facts are discussed