Ca(II) and Ba(II) methyl carbazate energetic complexes: syntheses, crystal structures, and properties.

New energetic materials, [Ca(MCZ)3(H2O)2](ClO4)2and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}n, are synthesized and tried as alternatives to common primary explosives. Both the crystal structures were determined by single-crystal X-ray diffraction. The crystal of [Ca(MCZ)3(H2O)2](ClO4)2belongs to the monoclinic, P21/c space group,a = 14.168(3) Å,b = 8.5938(18) Å,c = 18.889(4) Å,β = 111.234(2)°,V = 2143.8(8) Å3,ρ = 1.6893 g cm−3, and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}nbelongs to the triclinic, P-1 space group,a = 7.166(2) Å,b = 10.461(2) Å,c = 11.738(4) Å,α = 110.563(5)°,β = 93.799(2)°,γ = 96.864(3)°,V = 812.4(4) Å3,ρ = 2.185 g cm−3. Their thermal stabilities were investigated by differential scanning calorimetry (DSC), and exothermic peak temperatures with a heating rate of 10 °C min−1are 249.7 and 181.7 °C, respectively. Non-isothermal reaction kinetics parameters were calculated via both Kissinger’s method and Ozawa-Doyle’s method to work outEK = 124.6 kJ mol−1, lgAK = 10.38,EO = 126.7 kJ mol−1for the calcium complex andEK = 100.3 kJ mol−1, lgAK = 9.50,EO = 102.6 kJ mol−1for the barium complex. Additionally, the critical temperatures of thermal explosion, ΔS≠, ΔH≠, and ΔG≠were calculated as −231.2 J K−1 mol−1, 120.417 kJ mol−1, 236.728 kJ mol−1for the calcium complex and −230.6 J K−1 mol−1, 96.723 kJ mol−1, 195.938 kJ mol−1for the barium complex. As for their explosive nature, sensitivities toward impact and friction were tested. Both [Ca(MCZ)3(H2O)2](ClO4)2and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}nare insensitive to friction (>360 N); their impact sensitivities are acceptable (20 and 13 J). Both compounds are energetic complexes. [ABSTRACT FROM PUBLISHER]