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.

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