15 N and 13 C NMR study of acylated hydrazines. The instability of trifluoroacethydrazide in the solid state

Trifluoroacethydrazide is unstable even in the solid state with respect to hydrazonium N,N ′‐ditrifluoroacetyl hydrazinate, as shown by 15 N and 13 C NMR spectroscopy. The 1 H, 13 C and 15 N NMR data and rotamer distributions of formyl‐, acet‐ and trifluoroacet‐hydrazide and of N,N ′‐diformyl‐, N,N ′‐diacetyl‐ and N,N ′‐ditrifluoroacetyl‐hydrazine are reported and compared with the results of earlier investigations. A conformational dependence is observed for 1 J (NH) and 2 J (NH) in the formylhydrazides and of 1 J (NH), 2 J (NH) 3 J (NH) in the N,N ′‐diformylhydrazines. The conformational dependence of 2 J (CH) in formamide, reported in the literature, however, could not be confirmed.