Presentation and Discussion of the Principal Results

The results of interferometric determination of molecular structures present themselves in different ways and can be evaluated scientifically along different lines. 

We will first present the nunierk al data for some important organic linkages (Table 2). In order to confirm their reliability, values are occasionally added which have l)eon obtained by methods other than the interferometer method. The possil)ilities of application of these methods will be discussed in detail in the next section. The figures of Table 2 extend back to 1930 some more recent values are given in Table 3. 

By rc ason of this general constancy of th( primary valence bonds, quite sharp limitations are placed upon the basic assumptions of stereochemistry which are fully confirmed by modern research. These limitations restrict the possibility of synthesizing organic molecules and exclude many of those formulae previously used for purposes of convenience in designing structural formulae on paper. Our present knowledge authorizes and compels us to recognize and apply the constancy of the valence distances as an experimentally well-founded law in proposing any structural formula. It will be shown later by a few example s how important the consistent employment of this important principle has become in individual cases. 

In a second approximation we must, of course, expect exceptions to the law of constant valence distances, particularly if two united atoms carry substituents which on their part have special requirements with regard to charge shell. A review of the available experimental material actually shows that one and the same linkage in different molecules can under certain conditions exhibit values which differ from one another to a degree beyond the experimental error. An example of this shown by the figure on page 14 where the difference in the values obtained experimentally are certainly well outside the experimental error some experi- 

A Few Important Atomic Distances in Organic Molecules. Earlier Data 

---