Influence of the Z/E configuration on the ¹⁵N‐¹³C Coupling constants ^2,3J(¹⁵N‐¹³C) of Aromatic Azo and Diazo Compounds

A Photobasic Functional Group

“…These factors render the N1-nitrogen atom more electron rich than in the E isomer, and thus more basic. This model is bolstered by 15 N NMR data collected on the same general class of compounds in the early 1980s. − These studies observed a significant upfield shift in the N1-nitrogen signal with a minimal effect on the N3-nitrogen upon examination of the E vs Z isomer. Data from the same study suggest that a similar effect is true of simple azo-benzenes, but these compounds are generally so much less basic than 1 that the switching occurs in a less synthetically useful or observable range.…”