Über die Ringspannung in pentacyclischen Azofarbstoff‐Chrom(III)‐Komplexen

In pentacyclic chromium‐azo dyestuff complexes in which two azo dyestuffs in a vertical position to each other are so linked that a metal‐containing hetero ringis formed, the number of members of this hetero ring was systematically increased. The alterations occurring in the electron spectra express the change in the position of the two azo dyestuff residues or the change in tension occurring in the hetero ring. When the number of ring atoms is sufficiently large, which in this series of compounds was 15 (n = 10), the electron spectrum is identical with that of the «open» form, i.e. with that of the corresponding 1:2 complex devoid of this particular ring. The position of the two azo dyestuff residues, therefore, must be identical in both complexes, and this is only possible when the adjoining ring is completely free from tension. The phenomenon of ring tension can, therefore, be visibly followed in these examples.