1H nuclear magnetic resonance study of 1,10-phenanthroline in aqueous acid. Isolation of bis(phenanthroline)–perchloric acid

Abstract

The ¹H n.m.r. spectrum of 1,10-phenanthroline in aqueous acid has been examined as a function of acid concentration. Changes in the spectrum are consistent with the existence of three forms of protonated phenanthroline. At the highest acid concentrations (12M-HCl), diprotonated phenathroline (phenH₂²⁺) is the dominant species. When the formal concentration of acid equals that of phenanthroline, phenanthrolinium ion (phenH⁺) is present and can be precipitated with perchlorate ion. Further reduction of acidity gives phen₂H⁺, which has been isolated as a perchlorate salt.