Light Absorption as well as Crystal and Molecular Structure of <i>N,N</i>^′‐Dimethylindigo : An Example of the Use of Synchrotron Radiation

Abstract

The determination of physically meaningful thermal ellipsoids for hydrogen from X-ray diffraction data was achieved in the X-ray structure analysis of N, N′-dimethylindigo (1) by synchrotron radiation. Owing to the steric interactions of the CH3 groups with the carbonyl O atoms, the molecule is slightly twisted. This explains the bathochromic absorption of 1 in comparison to that of indigo and was also predicted from calculations.