Nitrogen-14 nuclear magnetic resonance. Part III. A unified scale for chemical shifts in organic and aqueous solutions

Abstract

A unified scale for ¹⁴N n.m.r. shifts, δ_N, based on internal standards, is proposed. The primary standards are nitromethane and nitrate ion for organic and aqueous solutions, respectively. The chemical shift between nitromethane and the nitrate ion is shown to be zero by means of internal standards. Tetranitromethane (+48 p.p.m.) and dimethylformamide (+276 p.p.m.) are suggested as secondary reference substances for small δ^N values.