Knowledge Bank

The rotational constants for trans $HC34S32SH$ and trans $HC32S34SH$ are differing so little that an assignment is difficult. The assignment was carried out by using the same basic set of equations as is used for deriving the Kraitchman relationship. These equations are used in a new way: They can be used to calculate the rotational constants of the fragment of the molecule not containing the position of the substituted atom. In the case of trans dithioformic acid the fragment, where the thiono-sulfur is extracted, is more prolate than the fragment, where the thiolo-sulfur is extracted. By using the equations mentioned, $Ia$ for the fragments are respectively found to be 2,74 $uA2$ and 6,40 $uA2$, in fair agreement with model calculations. I call the method the fragment method. The paper will give data and considerations concerning the assignment and the method.