[N2H5](+)(2)[N4C-N=N-CN4](2-): A new high-nitrogen high-energetic material

The reaction of [N2H5](+)(2)[SO4](2-) with barium 5,5 ' -azotetrazolatr gav e new high-energy-density materials (HEDM) based on the 5,5 ' -azotetrazola te dianion. The dihydrazinium salt of [N4C-N=N-CN4](2-) 1, its dihydrate 2, and its dihydrazinate 3 were prepared in high yield. Synthesis in water af forded yellow needles of [N2H5](2+)[N4C-N=N=CN4](2-). 2H(2)O (2): monoclini c, P2/c, a = 8.958(2) Angstrom, b = 3.6596(7) Angstrom, c = 16.200(3) Angst rom, beta = 96.834(3)degrees, V = 527.3(2) Angstrom (3), Z = 2; synthesis i n anhpdrous hydrazine gave yellow [N2H5](2)(+)[N4C-N=N-CN4](2-). 2N(2)H(4) (3): triclinic, P (1) over bar, a = 4.6208(6) Angstrom, b = 8.585(1) Angstr om, c = 9.271(1) Angstrom, alpha = 108.486(2)degrees, beta = 95.290(2)degre es, gamma = 102.991(2)degrees, V = 334.51(8) Angstrom (3), Z = 1. The compo unds were characterized by elemental analysis and vibrational (IR, Raman) a nd multinuclear NMR spectroscopy (H-1, C-13, N-14, N-15). The new compounds represent new high-nitrogen HEDMs with one of the highest nitrogen content s reported tu date ([N2H5](+)(2)[N4C-N=N-CN4](2-) 85.2%; [N2H5](+)(2)[N4C-N =N-CN4](2-). 2H(2)O 73.3%; [N2H5](+)(2)[N4C-N=N-CN4](2-). 2N(2)H(4) 85.7%). The standard heat of formation of the solvate-free compound 1 was computed at the MP2(FULL)/6-311+G(d,p) level of theory to be DeltaH degrees (f) = 2 64 kcal mol(-1), which translates to 1147 kcal kg(-1) and is one of the hig hest ever reported. The compounds are stable at room temperature, almost in sensitive to friction and impact, but detonate violently when the explosion is initiated, e.g., by rapid heating over the decomposition temperature or by using an initiator.