Der 1: 2‐Kobalt (III)‐Komplex aus einem o ‐Hydroxy‐ o ′‐alkylamino‐azofarbstoff im Vergleich mit dem durch Verbrückung erhaltenen analogen pentacyclischen Komplex

A pentacyclic Co III complex is described which is comparable with the tetracyclic 1:2 Co III complex from 2‐aminophenol‐4‐methyl‐sulphone → N‐ethyl‐2‐naphtylamine. Formally, the two ethyl groups of this latter dyestuff are eliminated in the new compound and replaced by a propylene group joining the two amine‐nitrogen atoms together. The pentacycle occurs in two forms: one with a single positive charge and one with a single negative charge. Both amine‐nitrogen atoms are protonated in the cation and deprotonated in the anion. The tetracyclic 1:2 complex cannot form a corresponding cation; it decomposes in acid medium. The stability of the cationoid pentacycle results from a positive chelate effect due to the additional ring. From the comparison of the electron spectra of the pentacyclic and the tetracyclic 1:2 complexes the author concludes that in the pentacyclic complex the azo dyestoff halves have merely undergone a displacement of position but no torsion.