Dediazoniation of Arenediazonium Ions in Homogeneous Solution. Part IX. Spectral Evidence for a Homolytic Mechanism Involving Pyridine Complexes

✍ Scribed by Hana Loewenschuss; George H. Wahl Jr.; Heinrich Zollinger

• Publisher: John Wiley and Sons
• Year: 1976
• Tongue: German
• Weight: 597 KB
• Volume: 59
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19760590505

✦ Synopsis

Abstract

The mechanism of dediazoniation of arenediazonium tetrafluoroborates in 2,2,2‐trifluoroethanol (TFE) is strongly dependent on the concentration of added pyridine. The added base complexes with the diazonium ion and diverts it to a homolytic pathway. Complex formation is indicated by the disappearance of the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus \equiv {\rm N}\raise1pt\hbox{---}$\end{document} stretching vibration and appearance of a new band at about 1640–1690 cm^−1^ ascribed to the \documentclass{article}\pagestyle{empty}\begin{document}$\raise1pt\hbox{---} {\rm N}\raise1pt\hbox{=\kern-3.45pt=} {\rm N}\raise1pt\hbox{---} \mathop {\rm N}\limits^ \oplus {\rm C}_5 {\rm H}_5$\end{document} system. UV. and NMR. results support this conclusion.

Chemically induced dynamic nuclear polarization (CIDNP) experiments clearly implicate a radical‐pair as an important intermediate in the decomposition of these complexes.