Temperature Effects on Nuclear Magnetic Resonance Absorption of Hydrogens Attached to Nitrogen

The nuclear magnetic resonance absorption of hydrogens attached to nitrogen (^(14)N) may show sharp, broad or triplet lines. Single sharp lines are obtained with amines and ammonia where exchange is rapid. Broad lines (10-75 c.p.s. at 40 mc.) are observed for many amides and pyrrole, while sharp triplet absorption has been observed for gaseous and completely anhydrous ammonia and ammonium ions in acid solution where N-H exchanges are slow. Triplet absorption is expected from spin-spin interactions between the protons and ^(14)N (I = 1).