Lola S. Deming

The Molecular Structure of P4O6, P4O8, P4O10 and As4O6 by Electron Diffraction

Molecular structures of P4O6 and As4O6 were determined from electron diffraction data. P4O6 was found to have the symmetry of the point group Td with an angle P–O–P of 128.5±1.5°, and a P–O distance of 1.67±0.03A. In this structure the phosphorus oxygen distances and the phosphorus valence angles were preserved with resulting deformation of the oxygen valence angle. The separation of the arsenic atoms in As4O6 was found to be 3.20±0.05A. Because of the predominant scattering of the arsenic atoms it was difficult to determine the oxygen valence angle, As–O–As. Values of 120°, 127.5° and 140° gave approximate agreement between the observed and calculated positions of maxima. Electron diffraction photographs obtained from P4O10 differ considerably from those found for P4O6. It was not possible to explain all of the features of the P4O10 diffraction pattern by a model having the symmetry of the point group Td and it is thought that the structure might be one of lower symmetry. Data were obtained on P4O8 which...

Electron Diffraction by the Oxides of Nitrogen

Electron diffraction has been obtained by the transmission of electrons (20–35 kv) through molecular beams of N2O, NO2, N2O4 and N2O5. The molecular structure determinations were made by using the complete electron scattering formula including the incoherent scattering. The results can be summarized as follows: (1) Nitrous oxide; for a linear model the separation of the end atoms was found to be 2.38±0.05A in exact agreement with Wierls measurement on this structure. Unfortunately it is impracticable to distinguish between models of the form N – O – N and N – N – O. (2) Nitrogen dioxide; no diffraction rings were observed which is to be expected if the molecule is triangular with the N – O distance 1.15 to 1.3A. (3) Nitrogen tetroxide; the presence of one diffraction ring at (1/λ) sin θ/2 = 0.455±0.01 lead to the conclusion that the N – N distance is 1.6 to 1.7A for the model O2N – NO2. No definite angular relationship between the two planes containing the NO2 groups could be determined. (4) Nitrogen pen...

Combination Frequencies Associated with the First and Second Overtone and Fundamental OH Absorption in Phenol and Its Halogen Derivatives

Absorption maxima occurring in the near infra‐red spectra of phenol and seven of its halogen derivatives have been measured and interpreted as combination frequencies in which the valence vibration of the OH group combines with frequencies of the body of the molecule. Certain of these absorptions underlie some of the trans‐peaks of the orthohalogen phenols causing such a trans‐peak to appear of larger area than that due to the trans‐peak alone. A group of the combination frequencies which lie in the range 1000–1600 cm—1 above the first overtone OH absorption have been observed as a group of an order of magnitude weaker intensity in the frequency range twice the values above the first overtone OH and also above the fundamental OH absorption, apparently involving two units of vibration in the combining frequencies. A close correspondence is found between the frequencies involved in these combination tones and the frequencies which have been observed in some of these compounds in the deep infra‐red and in Raman spectra.

A Partial Analysis of Some Infra‐Red Absorption Spectra of Organic Molecules in Dilute Solution

An attempt is made to resolve into component parts a number of relatively complex infra‐red absorption coefficient curves for several OH‐containing organic molecules in the region of the first overtone absorption of the OH group. Such analyses suggest certain relations between the structure of the molecule and its effect upon the character of the absorption of the absorbing group.