Vibration Spectra and Molecular Structure IV. The Infra‐Red Absorption Spectra of the Double and Single Molecules of Formic Acid

1938 ◽  
Vol 6 (9) ◽  
pp. 531-534 ◽  
Author(s):  
Lyman G. Bonner ◽  
Robert Hofstadter
1950 ◽  
Vol 18 (7) ◽  
pp. 990-991 ◽  
Author(s):  
L. H. Jones ◽  
J. N. Shoolery ◽  
R. G. Shulman ◽  
Don M. Yost

An investigation of the infra-red absorption spectra of five amino compounds (glycine, diketopiperazine, tetramethyl-diketopiperazine, glycylglycine and urea) has been made in the region 2-8-3-6 μ . The substances were used in the form of thin crystalline layers deposited on quartz windows. The spectra are discussed with regard to the molecular structure of the compounds under consideration. The number and position of the N—H frequencies in glycine and glycyl-glycine are in agreement with the assumption that these two molecules are in the zwitterion form in the crystal. The close similarity between the spectra of diketopiperazine and tetramethyldiketopiperazine on the one hand, and the amino acids and urea on the other, proves that no lactam-lactim interchange occurs in diketopiperazine and its derivative. Both compounds are shown to possess a centre of symmetry. It follows from the experimental evidence that in all the substances investigated resonance between the C—N and 0 = 0 bonds takes place.


The investigation of the molecular structure of organic beryllium compounds is being studied by one of us (W. R. A.) from the standpoint of their infra-red absorption spectra. During a mechanical defect in the infra-red apparatus the diamagnetic susceptibilities of basic beryllium acetate, propionate, and pivalate, and of beryllium acetylacetonate were measured in order to obtain further physical data on the structure of these molecules. The susceptibilities were measured on a Curie-Chéneveau magnetic torsion balance by the method previously described by Farquharson. Measurements were made at 18° C. The compounds were finely powdered in an agate mortar and packed tightly into a small graduated glass tube of very slight susceptibility. Packing of solids is most important in diamagnetic susceptibility measurements. In­ efficient packing leads to values of the specific susceptibility much lower than the true value. This diminution results from the fact that the volume of solid is virtually diminished by air spaces and a volume correction should be applied.


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