AbstractN,N′‐Dimethylhydrazine and several of its salts with energetic anions were synthesized and fully characterized by elemental analysis, DSC, mass spectrometry, multinuclear NMR (1H, 13C, and 15N) spectroscopy, and vibrational (Raman, IR) spectroscopy. According to the DSC measurements, the compounds exhibit good thermal stabilities, and the nitrate (2) and dicyanamide (4) salts belong to the ionic‐liquid type (i.e., Tm < 100 °C). Additionally, the solid‐state crystal structure of the nitrate [2: triclinic, P$\bar {1}$, a = 5.360(2) Å, b = 5.806(2) Å, c = 6.866(2) Å, α = 113.73(2)°, β = 92.44(2)°, γ = 90.08(2)°, V = 195.4(1) Å3], perchlorate [3: orthorhombic, Pbca, a = 11.774(2) Å, b = 11.072(3) Å, c = 14.050(3) Å, V = 1831.6(7) Å3], sulfate [5: monoclinic, P21/n, a = 5.913(1) Å, b = 9.509(1) Å, c = 10.351(1) Å, β = 90.29(1)°, V = 582.0(1) Å3], monopicrate [6b: monoclinic, P21/c, a = 10.910(1) Å, b = 6.7436(1) Å, c = 16.442(2) Å, β = 103.40(1)°, V = 1176.7(2) Å3], and dipicrate dihydrate [6·2H2O: monoclinic, P21/n, a = 8.230(1) Å, b = 13.024(1) Å, c = 10.642(1) Å, β = 104.43(1)°, V = 1104.7(2) Å3] salts were determined. Furthermore, a natural bond orbital (NBO) analysis of the structure of the [MeNH2–NH2Me]2+ cation was performed. Standard tests were used to examine the sensitivity of the compounds towards impact, friction, and electrostatic discharge. Lastly, the heats of formation of the compounds were calculated by means of quantum chemical calculations and used to determine the detonation parameters and specific impulses of the compounds and those of mixtures with an oxidizer.

AbstractThe ups and downs, and reasons therein, of the π‐complex theory of the mechanism of the benzidine rearrangements, and the possible role of π‐complexes in a newer understanding of the rearrangements, are described.