15N and 13C 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 15N and 13C NMR spectroscopy. The 1H, 13C and 15N 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 1J(NH) and 2J(NH) in the formylhydrazides and of 1J(NH), 2J(NH) 3J(NH) in the N,N′‐diformylhydrazines. The conformational dependence of 2J(CH) in formamide, reported in the literature, however, could not be confirmed.