Unexpected reaction of 4-(2,4,6-triphenylpyridinio)phenolate with urea in aqueous solution — structure of 1-(4-hydroxyphenyl)-2,4,6-triphenylpyridinium cyanate

✍ Scribed by Milart, Piotr ;Mucha, Dariusz ;Stadnicka, Katarzyna

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 312 KB
• Volume: 1995
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1995199511288

✦ Synopsis

Abstract

During crystallization of the pyridinium N‐phenolate dye 1 from a saturated aqueous solution of urea, 1‐(4‐hydroxyphenyl)‐2,4,6‐triphenylpyridinium cyanate (4) is formed unexpectedly as verified by IR, ^1^H‐NMR and X‐ray structural analysis. Such a course of reaction can be explained by the strong nucleophilic character of the betaine dye 1. The anion of 4, [NCO]^−^, is disordered between two positions; one of them can be assigned to an isocyanate and the other to a cyanate group. The nitrogen atom of the anion is involved in an intermolecular, nearly linear hydrogen bond with the hydroxy group of the cation whereas its oxygen atom is pointing towards the pyridinium ring of an adjacent pyridinium cation.