Isolation and Structure of a Hydrogen-bonded 2,2′:6′,2′′-Terpyridin-4′-one Acetic Acid Adduct

Abstract

Herein, we report the crystal structure of a key intermediate in the synthesis of 4′-substituted-terpyridines. Our findings confirm that the terpyridin-4′-one intermediate as generated from the condensation reaction of the corresponding triketone precursor with ammonium acetate is isolated as a hydrogen-bonded adduct with acetic acid, and not, as previously reported, as the acetate salt of a protonated pyridine nitrogen. This finding provides a rationale for the behaviour and structure of substituted terpyridin-4′-ones and pyridones in both the solid state and in solution.