2,5,8-Trihydrazino-s-heptazine: A precursor for heptazine-based iminophosphoranes

摘要

The title compound C_6N_7(NHNH_2)_3 (1) was obtained from melem C_6N_7(NH_2) _3 or melon [C_6N_7(NH_2)NH]_n and hydrazine by an autoclave synthesis. Upon treatment with a 10 % HCl solution it is transformed into the trihydrochloride [C_6N _7(NHNH_3)_3]Cl_3 (2). Compounds 1 and 2 were analysed with 13C NMR, ~(15)N NMR, FTIR and Raman spectroscopy. Furthermore, the single-crystal X-ray structure of the pentahydrate of 2 is reported (Pī, a = 674.96(3), b = 1214.17(6), c = 1272.15(6) pm, α = 66.288(2)°, /3 = 75.153(2)°, γ = 80.420(2)°, V= 920.30(8)-10~6pm~3, Z =2, T = 90(2) K). The thermal decomposition of 1 and 2 was investigated with TG/DTA. Reaction of 1 with NaNO_2/ HCl yields triazido-s-heptazine, C_6N _7(N_3)_3 (3). Tris(tri-n-butylphos-phinimino)-s- heptazine (4) was synthesised from 3 and characterised by means of ~(13)C, ~(31)P, ~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 retar-dants and (photo) catalysis.