2,5,8‐Trihydrazino‐s‐heptazine: A Precursor for Heptazine‐based Iminophosphoranes

The title compound C6N7(NHNH2)3 (1) was obtained from melem C6N7(NH2)3 or melon [C6N7(NH2)NH]n and hydrazine by an autoclave synthesis. Upon treatment with a 10 % HCl solution it is transformed into the trihydrochloride [C6N7(NHNH3)3]Cl3 (2). Compounds 1 and 2 were analysed with 13C NMR, 15N NMR, FTIR and Raman spectroscopy. Furthermore, the single‐crystal X‐ray structure of the pentahydrate of 2 is reported (P1̄, a = 674.96(3), b = 1214.17(6), c = 1272.15(6) pm, α = 66.288(2)°, β = 75.153(2)°, γ = 80.420(2)°, V = 920.30(8)·106 pm3, Z = 2, T = 90(2) K). The thermal decomposition of 1 and 2 was investigated with TG/DTA. Reaction of 1 with NaNO2/HCl yields triazido‐s‐heptazine, C6N7(N3)3 (3). Tris(tri‐n‐butylphosphinimino)‐s‐heptazine (4) was synthesised from 3 and characterised by means of 13C, 31P, 1H NMR, FTIR and MALDI‐TOF spectroscopy. Similar to s‐heptazine derivative 3, compounds 1 and 4 are precursors for graphitic carbon nitrides, which have attracted considerable attention recently, and to various potential applications, such as flame retardants and (photo) catalysis.