Aryldiazonium Salts as Nitrogen-Based Lewis acids: Facile Synthesis of Tuneable Azophosphonium Salts

Abstract

Inspired by the commercially available azoimidazolium dyes (e.g., Basic Red 51) that can be obtained from aryldiazonium salts and N‐heterocyclic carbenes, we developed the synthesis of a unique set of arylazophosphonium salts. A range of colours were obtained by applying readily tuneable phosphine donor ligands and para‐substituted aryldiazonium salts as nitrogen‐based Lewis acids. With cyclic voltammetry, a general procedure was designed to establish whether the reaction between a Lewis acid and a Lewis base occurs by single‐electron transfer or electron‐pair transfer.